There is a National Numbering Plan in use in the UK that is designed to make things simple and easy to use. The numbers used are intended to indicate the type of services they support and/or to give an indication of how much calls to those numbers cost.
The following table shows the main numbers used:
| Number | Sub-range | Use |
| 00 | - | Access for international calls. |
| 01 | - | National geographic numbers in the UK. |
| 02 | - | National geographic numbers in the UK. |
| 03 | 030, 033, 034 and 037 | National non-geographic numbers with calls charged at or below rates for geographic numbers. |
| 04 | - | Not used. |
| 05 | 0500 | Numbers where calls are free to the caller from BT Landlines - new numbers which are no longer allocated. |
| 055 | Corporate numbers. | |
| 056 | Location Independent Electronic Communications – typically VoIP services. | |
| 06 | - | Not used. |
| 07 | 070 | Personal numbers. |
| 076 | Radio paging calling. | |
| 071 – 075 077 – 079 | Mobile telephones. | |
| 08 | 0800, 0808 | National numbers where calls are free to the caller from BT Landlines. |
| 0820 | National numbers for Internet for Schools services. | |
| 0844 | National numbers. | |
| 0845 | National numbers. | |
| 0870 | National numbers. | |
| 0871, 0872 | National numbers, non-Internet. | |
| 09 | 090, 091 and 098 | Numbers for special services where premium rate call charges are applied. |
| 1 | Access to services and facilities. | |
| 100 | Operator. | |
| 112 | Emergency Assistance. | |
| 118xxx | Directory Enquiries. | |
| 141 | Withhold CLI. | |
| 2 - 8 | - | Not used in the National Number Plan but may be used for local dialling to geographic numbers and as ‘short codes’ from mobile telephones. |
| 9 | 999 | Emergency assistance. |
Information on call costs can be found in the BT Price List.
- Go to Section 2:Call Charges & Exchange Line Services
- Select the number range you're interested in i.e. 03xx numbers
- Look up the code i.e. 0300 is g21
- Then go Subpart 2:Calls Charged By Time Duration - Business
- Look for the type of call code i.e. g21-Calls to New Voice Services
- The pricing is shown in the right hand columns