| Code | DEF | Operator | Use | Notes
|
| 500 | | | |
|
| 500 | | Cable & Wireless Plc | | 9 Digit Numbers
|
| 5000-5511 | | | |
|
| 5511 | 00 | NPlusOne Limited | | 10 Digit Numbers
|
| 5511 | 40, 43-49 | BT | | 10 Digit Numbers
|
| 5511 | 55 | Teamphone.com Limited | | 10 Digit Numbers
|
| 5512-5516 | | | |
|
| 5516 | 50, 55, 60, 65 | BT | | 10 Digit Numbers
|
| 5517-5555 | | | |
|
| 5555 | 00 | FleXtel Limited | | 10 Digit Numbers
|
| 5555 | 08 | MCI WorldCom Ltd | | 10 Digit Numbers
|
| 5555 | 10 | FleXtel Limited | | 10 Digit Numbers
|
| 5555 | 50 | Nationwide Telephone Assistance Ltd | | 10 Digit Numbers
|
| 5555 | 55 | FleXtel Limited | | 10 Digit Numbers
|
| 5555 | 66 | Syntec UK Ltd | | 10 Digit Numbers
|
| 5555 | 84, 86, 88&89, 93 | Network Rail Infrastructure Limited | | 10 Digit Numbers
|
| 5556-5588 | | | |
|
| 5588 | 30-39 | Hutchison 3G UK Ltd | | 10 Digit Numbers
|
| 5588 | 80 | FleXtel Limited | | 10 Digit Numbers
|
| 5589-5600 | | | |
|
| 5600 | 00-04 | Magrathea Telecommunications Limited | | 10 Digit Numbers
|
| 5600 | 05 | BON.net Limited | | 10 Digit Numbers
|
| 5600 | 06 | Skycom Ltd | | 10 Digit Numbers
|
| 5600 | 07 | Coms Ltd | | 10 Digit Numbers
|
| 5600 | 08&09 | BON.net Limited | | 10 Digit Numbers
|
| 5600 | 10 | VODARE LTD | | 10 Digit Numbers
|
| 5600 | 11 | FleXtel Limited | | 10 Digit Numbers
|
| 5600 | 12-14 | IP Phone Services Ltd | | 10 Digit Numbers
|
| 5600 | 16 | Vectone Network Limited | | 10 Digit Numbers
|
| 5600 | 17 | Your Communications Ltd | | 10 Digit Numbers
|
| 5600 | 18 | Wightcable North Limited | | 10 Digit Numbers
|
| 5600 | 20 | Pipemedia Ltd | | 10 Digit Numbers
|
| 5600 | 21 | Blue Sky Ltd UK | | 10 Digit Numbers
|
| 5600 | 22 | FleXtel Limited | | 10 Digit Numbers
|
| 5600 | 24 | 24 Seven Telecom Ltd | | 10 Digit Numbers
|
| 5600 | 26 | Skymarket Limited | | 10 Digit Numbers
|
| 5600 | 29 | Telewest Communications Plc | | 10 Digit Numbers
|
| 5600 | 30 | Nexus Telecommunications plc | | 10 Digit Numbers
|
| 5600 | 31 | Blue Sky Ltd UK | | 10 Digit Numbers
|
| 5600 | 32 | Danemere Street Creative | | 10 Digit Numbers
|
| 5600 | 33 | FleXtel Limited | | 10 Digit Numbers
|
| 5600 | 35 | Nationwide Telephone Assistance Ltd | | 10 Digit Numbers
|
| 5600 | 36 | Square Systems | | 10 Digit Numbers
|
| 5600 | 38 | Cable & Wireless Plc | | 10 Digit Numbers
|
| 5600 | 40 | Coms Ltd | | 10 Digit Numbers
|
| 5600 | 41 | Blue Sky Ltd UK | | 10 Digit Numbers
|
| 5600 | 42 | MCI WorldCom Ltd | | 10 Digit Numbers
|
| 5600 | 43 | BT | | 10 Digit Numbers
|
| 5600 | 44 | Skymarket Limited | | 10 Digit Numbers
|
| 5600 | 45 | Cable & Wireless Plc | | 10 Digit Numbers
|
| 5600 | 46-49 | BT | | 10 Digit Numbers
|
| 5600 | 50 | BON.net Limited | | 10 Digit Numbers
|
| 5600 | 51 | Nordic Services Ltd | | 10 Digit Numbers
|
| 5600 | 52 | Band-X Limited | | 10 Digit Numbers
|
| 5600 | 54 | Griffin Information Systems Ltd | | 10 Digit Numbers
|
| 5600 | 55 | Coulomb Limited | | 10 Digit Numbers
|
| 5600 | 56 | Switch Services Ltd | | 10 Digit Numbers
|
| 5600 | 57 | COLT Telecommunications | | 10 Digit Numbers
|
| 5600 | 59 | Colloquium Ltd | | 10 Digit Numbers
|
| 5600 | 60 | BON.net Limited | | 10 Digit Numbers
|
| 5600 | 61 | Manx Telecom | | 10 Digit Numbers
|
| 5600 | 62 | DRD Communications plc | | 10 Digit Numbers
|
| 5600 | 63 | Telco Global Networks Limited | | 10 Digit Numbers
|
| 5600 | 64 | Thus Plc | | 10 Digit Numbers
|
| 5600 | 65 | Magrathea Telecommunications Limited | | 10 Digit Numbers
|
| 5600 | 66 | Skycom Ltd | | 10 Digit Numbers
|
| 5600 | 67 | NPlusOne Limited | | 10 Digit Numbers
|
| 5600 | 69 | Telco Global Networks Limited | | 10 Digit Numbers
|
| 5600 | 70-76 | BT | | 10 Digit Numbers
|
| 5600 | 77&78 | FleXtel Limited | | 10 Digit Numbers
|
| 5600 | 80 | BT | | 10 Digit Numbers
|
| 5600 | 81&82 | Manx Telecom | | 10 Digit Numbers
|
| 5600 | 84 | BON.net Limited | | 10 Digit Numbers
|
| 5600 | 86 | Vectone Network Limited | | 10 Digit Numbers
|
| 5600 | 88 | Callmonitor Ltd | | 10 Digit Numbers
|
| 5600 | 90&91 | Telephony Services Limited | | 10 Digit Numbers
|
| 5600 | 95 | Opal Telecom Limited | | 10 Digit Numbers
|
| 5600 | 96 | Inclarity plc | | 10 Digit Numbers
|
| 5600 | 97 | Wavecrest (UK) Ltd | | 10 Digit Numbers
|
| 5600 | 99 | Gamma Telecom Holdings Ltd | | 10 Digit Numbers
|
| 5601 | | | |
|
| 5601 | 00 | OciusB2 Limited | | 10 Digit Numbers
|
| 5601 | 01 | TELSTRA EUROPE LIMITED | | 10 Digit Numbers
|
| 5601 | 02 | Sala Limited | | 10 Digit Numbers
|
| 5601 | 10 | Prodigy Internet Ltd | | 10 Digit Numbers
|
| 5601 | 15-19 | BT | | 10 Digit Numbers
|
| 5601 | 20-24 | QiComm Ltd | | 10 Digit Numbers
|
| 5601 | 28 | Cable and Wireless (Energis) | | 10 Digit Numbers
|
| 5601 | 30-49 | BT | | 10 Digit Numbers
|
| 5601 | 51 | Colloquium Ltd | | 10 Digit Numbers
|
| 5601 | 55 | Affiniti Integrated Solutions Ltd | | 10 Digit Numbers
|
| 5601 | 56 | Connect Telecom UK Ltd | | 10 Digit Numbers
|
| 5601 | 66 | Premier Voicemail Ltd | | 10 Digit Numbers
|
| 5601 | 77 | Interweb Design Ltd | | 10 Digit Numbers
|
| 5601 | 80&81 | Coms Ltd | | 10 Digit Numbers
|
| 5601 | 83&84 | n-Tel Communications LTD | | 10 Digit Numbers
|
| 5601 | 90 | Excell Group Ltd | | 10 Digit Numbers
|
| 5602 | | | |
|
| 5602 | 00 | TG Support Limited | | 10 Digit Numbers
|
| 5602 | 02 | Syntec UK Ltd | | 10 Digit Numbers
|
| 5602 | 07&08 | Ready Technology Limited | | 10 Digit Numbers
|
| 5602 | 10 | Callagenix Ltd | | 10 Digit Numbers
|
| 5602 | 11 | The Number UK Limited | | 10 Digit Numbers
|
| 5602 | 15-19 | BT | | 10 Digit Numbers
|
| 5602 | 20&21 | Affiniti Integrated Solutions Ltd | | 10 Digit Numbers
|
| 5602 | 22 | C2C Ltd | | 10 Digit Numbers
|
| 5602 | 23-31 | BT | | 10 Digit Numbers
|
| 5602 | 32 | Caladan Communications Limited | | 10 Digit Numbers
|
| 5602 | 33 | Reality Telecom plc | | 10 Digit Numbers
|
| 5602 | 34-49 | BT | | 10 Digit Numbers
|
| 5602 | 50 | VTL (UK) Limited | | 10 Digit Numbers
|
| 5602 | 51-87 | BT | | 10 Digit Numbers
|
| 5602 | 88 | Connect Telecom UK Ltd | | 10 Digit Numbers
|
| 5602 | 89-99 | BT | | 10 Digit Numbers
|
| 5603-5999 | | | |
|