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A User's Guide to Telephone Numbering - 7 May 2003 Layout image
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Chapter 1 of this Guide sets out the differences between numbers that have a geographic area code eg ‘020’ for London and local number eg ‘7634 8700’. It covers:

Chapter 2 explains other types of numbers that can be dialled and the range of services available, and international number dialling. It covers:

Chapter 3 sets out Oftel’s role, why code and number changes occur, and recent number changes (at time of publication). It covers:

Chapter 4 looks at options available to consumers, and restrictions on number dialling. It covers:

Annex A provides details of the code and number changes provided for by Oftel since 1995.


Why are there so many different types of telephone number and what are they for?

Almost everyone in the UK has a home telephone number, and many also have a mobile telephone number. Businesses will have numbers for their switchboards and extensions and may have a special number for their call centre. Dialling a telephone number is straightforward: you dial all the digits in sequence. But within each geographic code area, you need only dial the local number. For example, if you are in the London code area (020) and you are dialling another number in the London code area you can just dial the local 8-digit number. However, the range of numbers and services available has increased significantly over the last few years, and consumers may not always be aware of the type of service they will receive, how the cost of calls may vary depending on the type of number dialled, or indeed what the number they are dialling signifies.

This Guide should help you to get a better understanding of what numbers mean, the type of services available, and the differences in the cost of calls depending on the number dialled.

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Chapter 1

Dialling the area code and number

1.1 The majority of consumers in the UK have at least one home telephone number. Some may have additional numbers for other uses, for example a fax machine, a dedicated number for their computer, or a number for business use. Businesses have numbers for their switchboards and extensions.

1.2 These numbers have an area code based on the area of the country you are situated in, followed by a local telephone number and are known as ‘Geographic’ numbers eg in London your number will have the area code ‘020’ followed by a local number such as ‘7634 8700’.

1.3 However, consumers do not always have to dial the area code. If you are calling someone within the same code area you can just dial the local number, eg if you are calling from within the Aberdeen code area (01224) and you wish to dial, from your landline phone, a number also within the Aberdeen code area, you can just dial the local number (you cannot do this from a mobile). Please note that if you wish to, you can dial the area code and the local number and still get through.

1.4 If you are calling from outside the Aberdeen code area you will always need to dial the code followed by the local number to get through. Also, if you are dialling from a mobile phone you will always need to dial the area code followed by the local number – this is discussed below.

1.5 The above example applies to most code areas in the UK. However, there are some exceptions to this. For example, Southampton and Portsmouth used to be in different code areas, but both now have the same area code ‘023’. Therefore, although customers are located in different areas, they can still dial each other using just the local number.

1.6 Within Northern Ireland, all calls within the province can be dialled using just the 8 digit local number.

1.7 There are also some area codes that share the first five digits. For example, the digits ‘01539’ are used for several code areas as follows:

01539 – Kendal

015394 – Hawkshead

015395 - Grange over Sands

015396 – Sedburgh

1.8 If you are dialling from one of these code areas to another of these code areas, you will need to dial both the code and number to get through. If you do not dial the code you will get a wrong number or get the number unobtainable announcement or tone.

Code and number lengths, and layout

1.9 The UK is currently split into over 600 area codes. (BT publishes a phone book companion that lists area codes). Most area codes start with the digits ‘01’ and are followed by 3 further digits, and in most code areas the local numbers following the area codes are 6 digits.

1.10 Since the code and number changes in the year 2000, most numbers in the UK have a 3-digit code beginning ‘02X’ followed by an 8-digit local number eg ‘020’ for London, ‘028’ for Northern Ireland, etc.

1.11 However, the lengths of area codes and local numbers can vary across the UK. The table below sets out the various combinations of area code and number lengths currently diallable within the UK:

Area Code length

Local number length (digits)


Area Code and Number (National Format Layout)

Code Area







(0151) XXX XXXX




(01204) XXXXX

Bolton (Daubhill)



(01865) XXXXXX




(015396) XXXXX




(016977) XXXX


1.12 Local numbers in geographic areas typically start with any digits except ‘0’, ‘1’ or ‘99’. In each code area with 6-digit local numbers there is approximately 790,000 numbers available, 7.9 million numbers in 7-digit areas, and 79 million numbers in 8-digit areas.

1.13 Oftel believes that confusion can be minimised by displaying a consistent number layout. Oftel recommends the layout for national format as shown in the table above, and international format (using the same examples) as follows (note that the leading ‘0’ of the area code should be omitted when calling UK numbers from abroad):

International Format Number Layout

Code Area

+44 29 XXXX XXXX


+44 151 XXX XXXX


+44 1204 XXXXX

Bolton (Daubhill)

+44 1865 XXXXXX


+44 15396 XXXXX


+44 16977 XXXX


(Note: ‘44’ is the international code for the UK, and should only be dialled from outside the UK. The ‘+’ indicates that there are digits dialled before the ‘44’ to make an international call eg ‘00’ are the digits dialled to make international calls from the UK. Many other countries eg all of Europe, also use ‘00’ for international calls).

How do code areas relate to the cost of a call?

1.14 If you are a BT or Kingston Communications (Hull) customer, then the cost of a call to a geographic number is usually dependent on where you are calling from and to.

1.15 The country is divided into over 600 Charge Areas. In the very large majority of cases, each Charge Area corresponds to one geographic code area. So, for example, the Rugby Charge Area is the same as the Rugby code area (01788).

1.16 If you are dialling within your own Charge Area or one adjacent to it, then the call will be charged as a local call. Beyond that, calls will be charged at the National call rate – see figure 1 below. (In a very few cases, calls to adjacent Charge Areas are charged at National rate).

Figure 1. Local Rate and National Rate calls to adjacent and non-adjacent code areas, respectively.



1.17 However, there are a few exceptions to this:

  • Some code areas are divided up into several Charging Areas. For example, Wearside, Durham, and Tyneside all have the same area code – ‘0191’ - (the first digit of the local number identifies which Charge Area you are calling). If you call from one of these areas, on a landline phone, to an adjacent code area then you will be charged at local rate. However, despite the same code area arrangements as above, if you call from another of these Charge Areas to a non-adjacent Charge Area, you could be charged at your telecoms providers national rate (see figure 2 below);

Figure 2. One code area covering several Charge Areas.




Equally, the new wide area codes, for example ‘023’, cover several Charging Areas. So even though Southampton can be dialled from Portsmouth using just the 8 digit local number, the call will be charged at national rate (see figure 3 below); and

Figure 3. One code area covering two Charge Areas

  • Some Charging Areas cover two area codes. For example, the area codes ‘01707’ (Welwyn Garden City) and ‘01727’ (St Albans) are both in the Colney Heath Charge Area (see figure 3, below). One effect of this is that while the ‘01727’ area is not adjacent to the London ‘020’ area, calls between them are charged at local rate, as Colney Heath and London Charge Areas are adjacent (see figure 4 below).

Figure 4. One Charge Area covering two code areas


1.18 Telecoms providers other than BT and Kingston Communications (Hull), do not tend to use code area charging, and charging methods vary between them eg some charge by time of day – daytime/evening/weekend – rather than by distance. Some cable companies may charge local rate across large areas eg any calls within Northern Ireland are charged at their local rate. Others may offer free calls to anywhere in the UK at specific times of the day, provided the call is to another of their customers.

1.19 Click here to see the section on BT’s website which give details of it’s customers specific local calling area.

1.20 In addition to the above examples, telecoms providers may offer ‘out of area’ numbers. Out of area numbers are Geographic numbers used, for example, by companies that may wish to have a ‘point of presence’ in London ie have a London telephone number(s), but be physically located for instance, in Manchester, as this may be more beneficial to the business. Callers are charged the normal rate by their telecoms provider for calls to London. However, calls are routed through to the company office in Manchester.

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Chapter 2

Mobile numbers

2.1 Over the last few years the number of people owning a mobile phone has increased considerably. Some people have more than one mobile eg one for work and one for personal use, and each mobile phone requires a mobile number so it can be dialled.

2.2 All mobile numbers in the UK currently begin with the digits ‘077’, ‘078’ or ‘079’ followed by another 8 digits, so there are 300 million numbers available for mobiles. Dialling mobile numbers always requires the full 11 digits.

2.3 Your mobile number is associated with the ‘SIM’ card inside your phone ie the small plastic square with the gold coloured microchip on it, located under the battery. The SIM card holds data that you may have entered using your mobile phone eg stored numbers of friends and family, additional ring tones, text messages, etc. The SIM card also holds information that is required by mobile providers to authenticate users.

2.4 If you wish to use another mobile phone without changing your mobile telephone number, in many cases you can remove the SIM card and place it in the mobile phone you wish to use. However, your SIM card may not be transferable to another mobile phone that has been subsidised by another mobile provider eg if you are a T-Mobile customer you may not be able to use your SIM card in a phone issued by Orange. This is known as SIM-locking and is used by mobile providers to protect handset subsidies. You should seek advice from your service provider.

2.5 In addition to your mobile number, SIM cards also hold another mobile number - the number of your personal voice mailbox.

2.6 Most people do not wish to remember a second mobile number, or to dial 11 digits every time to access their voice mailbox. Therefore, mobile companies offer short-cut keys to be used for accessing mailboxes eg by pressing one key on the mobile phone or by dialling a short code. The full mobile number of your mailbox is dialled when you use the short-cut keys.

2.7 When dialling any number from a mobile phone you should always dial the full national number eg if dialling landline numbers you should always dial the code followed by the local number. When calling a mobile number from a landline phone you should always dial the whole number eg 077 XXXXXXXX.

2.8 The cost of calls from mobile phones is often more expensive than calls from landline phones (eg your home phone), and call charges vary from one mobile company to another, and all offer many different call packages.

2.9 If you are on a mobile tariff that is distance related (for geographic calls) ie. calls to the code area you are calling from are different to calling other code areas, and you are making a call from your mobile, the nearest mobile station will identify your location, and you will be charged accordingly for the call.

Pager numbers

2.10 Pagers or "bleepers" are different to mobile and landline phones in that they can only be used to receive text messages or alerts. You cannot call a pager and leave voice messages, and you cannot make a call from a pager.

2.11 Every pager has a paging telephone number which begins with the digits ‘076’ followed by a further 8 digits. There are 100 million paging numbers available in the UK.

2.12 Pagers are used less and less these days as mobile phones have become more popular. However, pagers are still used by some organisations in preference to mobiles. Hospitals tend to issue pagers to staff, as mobile phones may interfere with medical equipment.

What are Personal Numbers?

2.13 Personal Numbers begin with the digits ‘070’ followed by a further 8 digits. Using one of these numbers, a call can reach you at many different locations. There are 100 million numbers available for Personal Numbering.

2.14 Personal Numbering services are available from general telecoms providers or from dedicated Personal Numbering service providers. Personal Numbering enables you to be called using a single telephone number (your ‘070’ Personal Number) and to receive those calls at virtually any telephone number. For example, you may choose to have calls to your Personal Number sent to your home phone between the hours of 8-9am, to your office phone between the hours of 9am-5pm, and to your mobile in the evenings.

2.15 The cost of calling Personal Numbers can vary considerably, and the cost is dependent on the type and complexity of the service chosen - calls routed to a mobile number, for example, are likely to be greater in cost than calls routed to a landline number. In some cases, calls to Personal Numbers may be free to the caller eg where you decide to use such a number to advertise your business, you could pay a high premium to a Personal Number provider to cover the cost of calls to your number. You should check with your telecoms provider if you are not sure of the cost of dialling a Personal Number.

Special Service numbers

2.16 Special Service numbers begin with the digits ‘08’. Special Service numbers, along with Premium Rate Service numbers (numbers beginning with the digits ‘09’ – discussed below) are known as Non-Geographic numbers ie the cost of the call is not related to the Geographic location, and callers are charged at the same rate whatever their location within the UK.

2.17 Special Service numbers are typically used by businesses and organisations as contact numbers or for advertising, but are also used for other services.

2.18 The most common Special Service numbers are shown in the table below, along with the starting digits and the typical cost to the caller:

Special Service

Numbers starting with digits:

Cost to the caller:



No cost from landline phones (mobile providers may charge – see below)

Local Rate


Charged at telecom provider’s Local Rate

Up to 5p


Any cost up to 5p per minute or up to 5p for the whole call

National Rate


Charged at telecom provider’s National Rate

Up to 10p


Any cost up to 10p per minute or up to 10p for the whole call

i) Freephone Numbers

2.19 Most Freephone numbers begin with the digits ‘080’ followed by a further 8 digits. However, you will also see Freephone numbers beginning with ‘0800’, followed by only 6 digits. Additionally, you will also see Freephone numbers beginning with ‘0500’, followed by a further 6 digits, although the amount of these in use is decreasing. Many Freephone numbers continue to be displayed as 0800 xxxxxx(x), but Freephone numbers beginning with the digits ‘0808’ also exist.

2.20 Calls to Freephone numbers are usually free to the caller. However, mobile companies may charge you for calling Freephone numbers – your mobile provider should provide an announcement stating that you will be charged for the call before the call is connected.

2.21 Freephone numbers are mainly used by businesses in advertisements. Businesses are charged by their telecoms provider for the cost of any calls to their Freephone number.

ii) Local Rate, Up to 5p, National Rate, and Up to 10p Numbers

2.22 Apart from Freephone numbers, you may also see other contact numbers for companies and organisations - Local and National Rate numbers, and ‘Up to 5p’ and ‘Up to 10p’ numbers.

2.23 Local Rate numbers begin with the digits ‘0845’ followed by a further 7 digits. National Rate numbers begin with the digits ‘0870’ followed by a further 7 digits. There are 10 million numbers available each for Local Rate and National Rate numbers.

2.24 The intention behind calling ‘0845’ and ‘0870’ numbers ‘local’ and ‘national’ rate was to give consumers an indication of call cost. The consumer would get a feel for the cost because it would be aligned to the cost of a geographic call. However, aside from BT, many operators do not charge the same for geographic and Special Service calls, and some do not have local and national rate tariffs at all. You should consult with your telecoms provider to find out the cost of calls to Special Service numbers.

2.25 Many ‘0845’ numbers are used to access the Internet, but as the computer usually dials the number automatically, callers may not be aware of the number used by their PC.

2.26 Other numbers in the ‘08’ range include ‘0844’ - ‘Up to 5p’ - and ‘0871’ - ‘Up to 10p’ - numbers. Many of these numbers are also used for Internet access at ‘unmetered’ or partially unmetered rates. You should contact your service provider for the cost of Internet calls from your computer.

2.27 Additionally, there are two unusual ‘08’ numbers used within the UK, in that they have shorter than expected number length. They are: 0800 11 11 for ChildLine; and 0845 46 47 for NHS Direct (used only in England and Wales).

Premium Rate Service ("PRS") Numbers

2.28 Premium Rate numbers typically begin with the digits ‘090’ or ‘091’ followed by a further 8 digits. There are 100 million numbers available for each of these ranges.

2.29 All premium rate services are regulated by the Independent Committee for the Supervision of Standards of Telephone Information Services ("ICSTIS") – please see below for more information about ICSTIS and its work.

2.30 When you dial a ‘090’ Premium Rate number, you receive some form of content, product or service from the call; for example, entry to competitions, voting, horoscopes, chatlines, etc. Services can be accessed in many ways – by phone (fixed and mobile), fax, PC and interactive TV.

2.31 The next digit after the ‘090’ indicates the type of service and/or potential cost of the call. In addition, ICSTIS requires that call costs be given in advertising material. These should be given either on a per minute basis or for the total cost of the call, and should be inclusive of VAT. For certain types of service (for example, all services featuring live conversation), ICSTIS also requires that call costs be given at the start of the service.

2.32 Where callers are likely to call a premium rate service from a mobile phone, the advertising material must state that calls from mobile phones are likely to cost more than calls from landline phones.

2.33 The potential call costs based on the digits dialled is as follows (please note that the call costs given below relate to calling from a landline phone):

‘0900’ and ‘0901’ – calls cost up to 60 pence per minute with the cost of a call capped at or below £5 ie. the total cost of the call should not exceed £5.

‘0904’, ‘0905’ and ‘0906’ – calls costs up to £1.50 per minute, and there may or may not be a call cap ie. unlike the tariff range above, there does not have to be a maximum cost for the call.

Note: To minimise the risk of excessive phone bills, ICSTIS requires that certain types of service are limited in cost (for example, consumer credit services). Generally speaking, such services must disconnect automatically when the maximum call cost has been reached. Other services (for example, dating services) must give call cost warnings at regular intervals. ICSTIS also has strict rules to stop services being unnecessarily lengthy.

‘0907’ – these numbers can be used to buy products or services, for example, the cost of a call for, say, 10 minutes may be £15, but you may receive a music CD in the post as a result of the call – in effect, you are paying for the CD through your telephone bill.

‘0908’ and ‘0909’ – these numbers are for services of an ‘adult’ (sexual entertainment) nature, and costs will vary.

‘091’ – these numbers are for ‘non-content’ premium rate services. Such numbers may be used to access e-mail or some other value added telecoms service. Some companies use ‘091’ numbers to provide international call connection.

2.34 Premium Rate Service numbers, like other numbers, can be barred from being dialled from your phone – see below for details on call barring).

Short Code services

2.35 Most people are aware that you can obtain a variety of services by dialling short codes from your phone. For example, dialling ‘100’ should put you through to the operator service. However, not everyone is aware of all the services that may be available to them. The table below sets out the short codes that may be used by all telecoms providers ie. whichever telecoms provider you are with, if they wish to supply any of the services below, they should use the relevant code(s) indicated:




Assistance Operator


International Assistance Operator


Emergency Services


Emergency Services (mobile and European standard)


National Directory Enquiries (up to Aug 2003)


International Directory Enquiries (up to Aug 2003)


Directory Enquiry services (details below)


Directory Enquiries for Blind or otherwise disabled customers


Speaking Clock


Withhold Calling Line Identity


Number Release (Do not withhold CLI)


Call Return


Erase 1471 memory


Automatic Call Trace


Activate Call Screener


De-activate Call screener


Voice Text Network ("VTN") Services for the Hearing Impaired - Emergency Service


Voice Text Network ("VTN") Services for the Hearing Impaired - Text Service


Voice Text Network ("VTN") Services for the Hearing Impaired - Voice Service

(Note: the emergency code ‘112’ is a European and mobile standard, so you should be able to dial it for emergency assistance when you go abroad – anywhere in Europe, and anywhere else in the world that you can use your own mobile phone).

2.36 Not all telecoms providers offer all the services shown in the above table, and they are not obliged to offer any of the services except the ‘112’/’999’ emergency service, an assistance operator ‘100’, and a Directory Enquiry service.

2.37 In addition to the services shown above, some telecoms providers may offer other services behind short codes for use by their own customers or employees. The codes used may be 3, 4, 5 or even 6 digits ie. of the format 1XX, 1XXX, 1XXXX and 1XXXXX.

2.38 The range of services offered behind such short codes can vary from one telecoms provider to another and particularly between mobile and non-mobile telecoms providers. For example, some operators use ‘150’ for customer services, while others may use a different code or method for obtaining customer services.

2.39 In addition to the short codes used for services described above, short codes may also be used on some networks (eg BT’s and Kingston Communications (Hull)’s) to allow access to competing service providers’ networks. This is called ‘Indirect Access’ and the codes are in the form 1xx, 1xxx or 1xxxx. You dial these codes before dialling the normal number you wish to reach.

(Note: in a few cases, you may need to wait for a second dial tone after dialling the Indirect Access code. Your Indirect Access service provider will tell you what you need to dial).

2.40 Instead of the telephone call being routed across your normal telecoms providers’ network, it is routed via the network used by the owner of the code you have dialled. The Indirect Access provider bills you separately for the calls you make via them, so you have to have a service contract with them before you can use these numbers.

2.41 The type of Indirect Access services available and the charges for calls will vary. For example, some Indirect Access providers may charge you a monthly fee for being able to make calls, while others only charge for calls. Some will require payment in advance by maintaining a cash credit with them.

Golden Numbers

2.42 Telecoms providers can sell specific numbers that are memorable or have particular significance to a company - often referred to as ‘golden’ or ‘choice’ numbers as they can be worth more commercially. For example, numbers with repeating digits such as 0808 888 88XX. Other numbers such as the London number (020) 2020 2020, for example, may be beneficial to a business as it has a memorable number string.

Alphanumeric Numbers

2.43 If you look on a telephone keypad you will often see a series of letters next to most of the digits. The letters can be used to ‘replace’ digits of a telephone number to make up a word or words. This is known as an alphanumeric number as the number includes letters of the alphabet.

2.44 There is currently no regulation within the UK or Europe on standard keypad layout. However, to avoid confusion and potential mis-dialling, the European recommended layout of letters on a standard keypad is:





No letters


















No letters

2.45 Businesses may prefer to use an alphanumeric to advertise their company, as it is often easier to remember than the telephone number. A company name such as NUMBERS, for example, may use the alphanumeric - 0845 NUMBERS. To call 0845 NUMBERS you would dial the digits - 0845 6862377.

2.46 Some companies may wish to use a name longer than the standard 11 digits as it may fit their company name better eg 0845 NUMBERING. However, the number will begin to connect after the 11th digit is dialled – dialling the 12th, 13th or 14th digit will usually make no difference. However, on some mobile and cable networks, dialling these excess digits can make the call fail.

2.47 Please note that composing text messaging from mobile phones is a totally different use of letters to alphanumeric dialling, as it requires the pressing of a numeric key a different numbers of times to produce the letter required.

International Number Dialling

2.48 Making a call to another country from the UK is a little more complex than dialling within the UK.

2.49 Firstly, in order for the call to leave the UK and reach the country you are dialling, you need to dial the international code ‘00’ followed by the country code eg ‘1’ for the United States of America and Canada.

2.50 You will then need to dial the full national number, usually consisting of the area code followed by the local number. However, you should remember to leave off the leading ‘0’ of the full national number (or leading ‘1’ in the case of North America). In most cases this does not need to be dialled for international calls.

2.51 However, in some countries such as Italy, you do not leave off the leading ‘0’ - you should consult your telecoms provider for advice on which countries require the leading ‘0’ to be dialled when dialling internationally.

2.52 The table below shows the general international dialling format:

International Dialling Format

00 + country code + full national number (leaving off leading ‘0’)

2.53 When dialling UK numbers from abroad on a landline phone, you have to dial the international code from that country (NB. not all countries use the same international code) followed by ‘44’ for the UK. You then dial the area code (leaving off the leading ‘0’) and then the local number (or the whole number if dialling a mobile or other type of number).

2.54 Some numbers may not work when dialled from abroad. For instance, in some countries, telecoms providers may not allow ‘0845’ Local Rate numbers, ‘070’ Personal Numbers, etc. to be dialled from their phones. It’s worth checking before you go whether an alternative (usually geographic) number is available for dialling from abroad. This could turn out to be invaluable in an emergency, for example if you were to lose a credit card.

2.55 Even where these numbers may be dialled, it is important to note that the cost of dialling them is usually more expensive than dialling the same number from within the UK, and is some cases it may be very expensive. You should check with the telecoms providers in the country you are dialling from about the cost of dialling such numbers.

2.56 Dialling UK numbers from abroad is different on your mobile. Firstly, you have to get a ‘roaming agreement’ with your mobile provider before making a call abroad. When you try to use your mobile, the nearest mobile station in that country will send a signal back to your home base in the UK which will identify where you are calling from. The charges for making a call from abroad on a mobile are usually a lot higher than calls made within the UK. Your mobile provider should be able to inform you of the call costs.

2.57 If you dial from abroad back to the UK, you must remember to dial the International access code and the country code ‘+44’ (missing off the leading ‘0’ of the full national number), where ‘+’ signifies the appropriate international access code for the country from which you are calling. Most mobile phones allow you to store numbers with the prefix +44 especially for this (and you can generally use the same stored number to make calls within the UK, and they should be charged at normal national, not international, rates).

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Chapter 3

Oftel’s role in managing the UK’s telephone numbering

3.1 Oftel is responsible for managing the UK’s telephone numbers and developing numbering strategy in the national interest. This means that Oftel is responsible for developing the structure of numbering to ensure that it is clear to customers and for ensuring that there are sufficient numbers available to meet all reasonable demands that customers and telecoms providers might have.

Oftel’s role in issuing telephone numbers to telecoms providers

3.2 Oftel is responsible for issuing all types of telephone numbers used within the UK to telecoms providers. Over 400 of these currently have numbers and codes. This includes Geographic numbers, Mobile numbers, Local Rate and National Rate numbers, Premium Rate Service numbers, Indirect Access Codes, etc.

3.3 Number ranges are typically in blocks of 10,000 for Geographic, most Special Service numbers, and Premium Rate Service numbers, 100,000 for other numbering such as Personal Numbers, and in blocks of one million for mobile numbers.

3.4 Telecoms providers apply to Oftel for specific number ranges and/or codes. Oftel carries out checks on companies applying for numbers and only issues to those who meet specific criteria eg having a suitable telecoms system. This avoids giving out numbers, which are a scarce resource, to companies that are not entitled to them.

3.5 Telecoms providers then either issue numbers to customers directly or they may use another company to sell the numbers and services on to consumers.

3.6 The Channel Islands (Guernsey and Jersey) and the Isle of Man have their own regulatory organisations, similar to Oftel. Although they are outside the UK, they all use numbers from within the UK system and each has it’s own area code.

3.7 Oftel publishes details of Numbering issues on it’s website. Click here to see the Numbering page.

Changes to telephone numbers within the UK

3.8 Apart from issuing numbers to telecoms providers, Oftel is also responsible for ensuring that there are sufficient telephone numbers available to meet the UK’s demands for the foreseeable future.

3.9 Oftel can reasonably estimate the demand for existing services by current telecoms providers. However, there is no easy way of predicting demand for innovative services that telecoms providers may introduce and which may require a large amount of telephone numbers. Also, the numbering capacity required generally is affected by the number of telecoms providers competing in the telecoms market, and this too can be difficult to predict.

3.10 Annex A, below, sets out code and number changes that Oftel has made to ensure that there is sufficient numbering for current and future demand. At the same time Oftel has had to ensure that numbers are fitted into logical groups so that consumers can identify the type of number they are calling eg that mobiles begin with ‘077’, ‘078’ or ‘079’, and the likely cost of the call.

i) Number changes

3.11 Oftel typically changes numbers in areas where numbering is getting short. To change numbering otherwise would cause unnecessary expense for telecoms providers and businesses (eg changing advertising, etc.) and confusion for customers changing their telephone number.

3.12 Although code areas and numbers may change across the UK, such changes do not affect call charges ie. telecoms providers do not charge any differently as a result of any code or number changes.

3.13 Some people have questioned why there have been three code changes in London in 10 years. Changes in London are obviously higher profile, however other areas have also experienced code changes in the past.

3.14 The reason for the changes in London is that, in the late 1980s, before Oftel took over management of the UK numbering from BT, London’s ‘01’ code was on the verge of running out of numbers. Capacity was doubled in 1990 by splitting the area into two – inner/outer London, using the codes ‘071’ and ‘081’.

3.15 London codes changed to ‘0171’ & ‘0181’ in July 1995 as part of the PhONEday number changes (re-using the ‘01’ prefix released in 1990 when London changed to ‘071’ and ‘081’). This didn’t give London any extra numbers, but it did create a huge pool of unused numbers – ‘02’ to ‘09’ - an extra eight billion numbers for use for other services, as discussed above.

3.16 The original doubling of London capacity in 1990 was only ever considered as an interim measure. The change to the ‘020’ London code in 2000 provided five times as many numbers again (10 x the amount of London numbers that existed prior to the 1990 changes) and also re-enabled local dialling again across the whole London area.

3.17 When the 020 7XXX XXXX and 020 8XXX XXXX numbers start to run out, Oftel will be able to issue further numbers such as 020 3XXX XXXX.

ii) Will there be any further number changes?

3.18 Although the number changes in 2000 created a huge pool of numbers for different services, there will probably need to be changes to individual towns and cities if they become in danger of running out of numbers. If this occurs, the areas affected are likely to be changed to wide area codes (3-digit codes) eg ‘02X’. Several existing code areas around the same geographical location may be fitted into the same wide area code.

3.19 This has already occurred in some areas eg Portsmouth and Southampton now have the code ‘023’, and the whole of Northern Ireland has the code ‘028’.

3.20 However, before any code and number changes are decided, Oftel carries out a local consultation in the area(s) affected to ensure that local issues and concerns are taken into consideration.

3.21 There is usually at least two years’ notice of changes to codes and numbers, and a period of ‘parallel running’ ie. a period of time during which you can dial the old code and old number or the new code and new number, and still get through. This gives people time to get used to the new telephone numbers.

3.22 Also, there are a few code areas within the UK that have 4-digit or 5-digit local numbers. These are likely to be changed to 8-digit local numbers (with a 3-digit code) to fall in line with the rest of the UK, although there is currently no set date for these changes.

iii) Recent number changes – directory enquiry services

3.23 A recent change to numbering in the UK is the change in short codes for directory enquiry services. The changes were necessary to help promote competition in the market for directory enquiry services in order to provide customers with a greater variety of directory enquiry services, at a range of competitive prices.

3.24 Oftel had to decide on a range of short codes (to replace the old directory codes – ‘192’, ‘153’, etc.) that would be relatively easy for consumers to remember, and to ensure that there were sufficient codes available to issue to telecoms providers both now and in the foreseeable future.

3.25 Directory services now begin with the digits ‘118’ followed by a further 3 digits, ie. 118XXX, which is in line with other European countries’ use of ‘118’ for directory enquiries. You should contact your telecoms provider for details of the range of services available, and the costs of calling them.(Directory enquiry codes ‘192’ for national and ‘153’ for international, cease to be in service from August 2003).

3.26 Oftel has produced a ‘Consumer Guide to the new 118 directory enquiry services’.

3.27 There is also an independent website with details of 118 services and prices known as

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Chapter 4

Restrictions on dialling numbers

4.1 When Oftel issues number ranges to telecoms providers, they contact each other to allow them to make arrangements so that their customers can dial numbers in ranges issued to other telecoms providers, as well as to numbers issued to themselves.

4.2 Only BT and Kingston Communications (Hull), however, are obliged to ensure that their customers can dial all numbers within the UK. Therefore, if you are with any other company you may find that you cannot dial certain numbers - in the main, the only significant group of numbers you may not be able to dial are the Indirect Access codes used to connect to competitors’ networks. Also, some other short codes may have different meanings.

Can I keep my number when I change address?

4.3 Depending on the abilities of a particular telecoms provider’s network you may be able to keep your number if you move within the same locality, but not if you move to a different code area. However, using ‘out of area’ numbers (discussed above) may allow you to keep your number.

Can I keep my number when I change telecoms provider?

4.4 Whether you are a residential or business customer, you may wish to change your telecoms provider, for example to get cheaper calls or a better service. However, you may want to keep your old number rather than take a new number perhaps because it’s vital to your business or just because you want to avoid the hassle and costs of changing number.

4.5 You are entitled to keep your telephone number if you change telecoms provider while keeping the same kind of service no matter what type of telephone number you have (except paging numbers). Telecoms providers are obliged to provide this service, but it only covers circumstances where you want to change telecoms provider, not where you want to move location and keep your old number (discussed above).

4.6 This is known as ‘number portability’ or ‘porting’ your number to another telecoms provider. Just tell your current or preferred supplier that you want to keep your old number. In some cases you may be charged an administrative fee for this service - you should check with your current telecoms provider and with the provider you wish to transfer to.

4.7 When you port a mobile number to another mobile provider there may be some confusion over charges applied to that number. Charges for calls from landline phones to a ported mobile number stay the same as they were before. However, for calls from mobile phones, charges may increase when you call someone who was with the same mobile provider as you, but has ported their number to a different mobile provider. But, where the person you are calling has ported their number to the same mobile provider as you, lower charges normally apply. Other than that, charges usually stay the same.

4.8 If you want to find out whether a number you wish to call is on the same mobile network as you, you should contact your mobile provider.

Making calls via another telecoms provider

4.9 If you don’t want to change telecoms provider, but you still wish to make calls via another telecoms provider, for example, to get cheaper international calls, there are services that may allow you to do this: Indirect Access (discussed above in ‘Short Code Services’); and ‘Carrier Pre-Selection ("CPS").

4.10 CPS is similar to Indirect Access in that you can choose to make calls via another telecoms provider. However, you do not have to dial a short code. Your CPS provider may provide you with the option of routing just your national calls, or just your international calls or all of your calls. They pre-set your phone system to ensure you are connected to and billed by the CPS provider for the calls routed by them.

4.11 Even if you opt for CPS, you can still choose to override the CPS options either by using an Indirect Access code or by using a code to revert to your regular provider.

Calling Line Identification ("CLI") services

4.12 You may be aware of services available from your phone, which allow you to find out the number of the last person who called you, and other associated services, by dialling short codes typically beginning with the digits ‘147’. These services are known as Calling Line Identification services.

4.13 The most common of these is ‘1471’ which allows you to find out the number of the last person who called you, and ‘141’ to withhold your number being displayed to the person you are calling.

4.14 There are also other services available, which your telecoms provider may or may not provide for their customers. The short codes used to dial these services are shown in the table of short codes, above.

4.15 In addition to CLI services provided by your telecoms provider, some companies offer specific CLI services to which you can subscribe. For further details of these, and other information on CLI services, please refer to Oftel’s ‘A Consumer’s guide to Calling Line Identification services’.

Ex-directory service

4.16 Some people may not wish others to know their telephone number or address. Therefore, it is possible to choose to have your number and address stored as 'ex-directory' when you take out a telephone service ie. it will not be listed in any telephone directory or given out by directory enquiry services. This is useful if, for example, you wish to keep your address private. You can also choose to have your number available through Directory Enquiries, but not in the Phone Book.

4.17 However, you should be aware that the ex-directory service might not, necessarily, protect you from unwanted sales and marketing calls. If you don't wish to receive these calls you should register with the Telephone Preference Service ("TPS") at via the Internet or on the telephone 0845 070 0707. Once your number is registered you should stop receiving such calls (mobile numbers can also be registered with TPS). It will take 28 days for your number to be added to the TPS' list of registered numbers. If you do receive any calls after this period you can ask the TPS to take further action.

4.18 You may also register with the TPS to prevent unwanted sales and marketing SMS text messages to your mobile phone.

4.19 You should also be wary of adding your telephone number when entering competitions or filling in questionnaires. The small print at the bottom usually states that your details may be used to advertise future products, or may be used by related companies. This may result in unwanted phone calls.

Nuisance calls

4.20 If you are being pestered by someone who keeps ringing your number (ie nuisance calls) your telecoms provider may be able to help, or even change your number. However, you will need to weigh up the benefits of changing your number against having to inform everyone of your new number.

Can I block specific numbers being dialled from my phone?

4.21 If you are concerned about specific numbers being dialled from your phone because of the high cost of the calls or the content of them eg adult services, you can ask your telecoms provider to block specific number ranges. Some telecoms providers may offer this facility for free, others may charge. This is known as ‘call barring’.

4.22 However, customers cannot have individual calls barred - calls are barred on a whole range. Therefore, you would not be able to dial any other numbers in that range. You would need to weigh up the benefits of barring calls against not being able to dial others numbers starting with the same digits.

4.23 Some telecoms providers offer a customer-controlled barring product (using a PIN number) that could be used, for example, to ensure that only you (as the bill payer) can make international or PRS calls from your phone.

The Regulation of Premium Rate Services

4.24 The organisation in the UK that regulates the content and promotion of premium rate services (typically numbers beginning ‘090’ or ‘091’) is the Independent Committee for the Supervision of Standards of Telephone Information Services ("ICSTIS").

4.25 ICSTIS regulates premium rate services through its Code of Practice, which sets out the rules with which all premium rate service providers must comply. ICSTIS aims to prevent consumer harm by requiring clear and accurate pricing information, honest advertising, and appropriate and targeted promotions.

4.26 Where problems occur, ICSTIS investigates complaints and has the power to fine companies and bar access to services. ICSTIS can also formally name the individual behind a company and bar that person for a defined period from running any other premium rate services under any company name on any telephone network.

4.27 If you have any concerns about the promotion or content of any premium rate service, you should contact ICSTIS on its free helpline at 0800 500212 or use the online complaints form at Alternatively, you can write to ICSTIS at FREEPOST WC5468, London SE1 2BR.

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Annex A

A.1 Oftel has decided on necessary changes to the format of telephone numbers within the UK, in order to accommodate demand from the telecoms industry and to allow numbers to be fitted into logical groups to make it clearer for consumers.

A.2 Number changes have to be made in stages so that old and new numbers may be dialled together for a period of time so that customers get used to the new numbers. After that, the old number will have a recorded announcement stating that the number has changed. Finally, the old numbers are removed and will be held for a period of time eg two years before being used again for other services.

A.3 The main number changes Oftel has provided for are set out below in chronological order.

i) PhONEday – July 1995

A.4 In July 1995 Oftel changed all Geographic area codes to begin with ‘01’. This was known as PhONEday. This number change managed to free-up codes that could be used for other types of services that were becoming popular such as Premuim Rate and Mobile, as well as to allow for future new services that may require vast numbering resource. This change was facilitated by the 1990 change to the ‘01’ London code to ‘071’ and ‘081’.

A.5 The table below shows how numbers were used before July 1995:

Number prefix

Example of Geographic use

Other services using the number prefix


Not used

Freephone, Local Rate, Premium Rate Services


Aberdeen (0224)

Not used


Dover (0304)

Freephone, Mobile, Local and National Rate, Premium Rate Services


Gloucester (0452)

Mobile, National Rate


Kinross (0577)

Freephone, Mobile, National Rate


Newbury (0635)

Local Rate, Premium Rate Services


Romford (0708)

Personal Numbers


Tamworth (0827)

Freephone, Mobile, Local and National Rate, Premium Rate Services


York (0904)

Freephone, Mobile, Local and National Rate, Premium Rate Services

A.6 After PhONEday, numbers previously used in Geographic areas (those beginning with ‘02’ – ‘09’) were held for a period of at least two years to allow changed number announcements on them, and to prevent customers mis-dialling.

A.7 The numbers made free by the PhONEday changes in 1995 were used in the next code change in the year 2000. This was known as the National Code and Number Change.

ii) National Code and Number Change – April 2000 (The Big Number campaign)

A.8 The table below shows the how UK numbers are used following the National Code and Number Change ("NCNC") in April 2000.

Numbers beginning

Typical use


Geographic use


Geographic use


Future Geographic use


Future services


Corporate Numbering


Future services


Personal Numbering, Paging and Mobile


Special Services eg Freephone, Local Rate, National Rate


Premium Rate Services

A.9 Oftel needed to introduce the NCNC changes as a result of the explosive growth in demand for numbers caused by the needs of new telecoms providers, and residential and businesses customers increasingly having more than one telephone line in their home – for their PC, maybe another for a fax, and new services being offered by telecoms providers which involve different numbers for individual members of the family.

A.10 Some areas of the UK had number changes: London, Coventry, Cardiff, Portsmouth, Southampton and all of Northern Ireland. In addition, mobile numbers changed to cope with the huge growth in mobiles – millions of people now have a mobile phone. Other numbers such as Local and National Rate, and Premium Rate numbers also changed.

A.11 The NCNC number changes created a vast resource of numbers. However, the overall result of the PhONEday and NCNC changes was to allow numbers to be fitted into logical groups, instead of being all over the place as shown in the table of pre-July 1995 numbering, above.

A.12 Oftel believes the structure of UK numbering is sound, and should provide sufficient numbering capacity long into the future. Also, the logical grouping of numbers eg mobile numbers beginning ‘077’, ‘078’ or ‘079’, makes clearer to consumers the type of number they are dialling and the likely cost.

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