| 01243 11 | IP Voice Networks Ltd | 22/08/2017 |
| 01243 20 | AQL Wholesale Ltd | 01/11/2004 |
| 01243 21 | Gamma Telecom Holdings Ltd | 05/04/2004 |
| 01243 22 | BT | 03/08/1994 |
| 01243 24 | Vodafone Ltd (Thus) | 17/01/2012 |
| 01243 250 | Linear Telecoms Limited | 05/10/2010 |
| 01243 251 | Sky UK Limited | 21/06/2013 |
| 01243 252 | Invoco Ltd | 21/09/2011 |
| 01243 254 | Internexus Networks Limited | 18/11/2011 |
| 01243 255 | Tuxtel Ltd | 21/12/2011 |
| 01243 256 | Simwood eSMS Limited | 01/02/2012 |
| 01243 257 | Bicom Systems EURL | 02/03/2012 |
| 01243 259 | API Telecom Limited | 26/03/2012 |
| 01243 26 | BT | 15/07/1994 |
| 01243 270 | Inclarity Communications Limited | 06/12/2010 |
| 01243 271 | Inclarity Communications Limited | 06/12/2010 |
| 01243 272 | Inclarity Communications Limited | 06/12/2010 |
| 01243 273 | IOVOX Limited | 03/04/2012 |
| 01243 274 | Ziron Limited | 27/07/2012 |
| 01243 275 | Inclarity Communications Limited | 03/12/2010 |
| 01243 276 | Sky UK Limited | 21/06/2013 |
| 01243 277 | Numbergroup Utilities Ltd | 29/04/2019 |
| 01243 278 | TalkTalk Communications Limited | 06/09/2012 |
| 01243 279 | ICC Networks Ltd | 12/04/2012 |
| 01243 280 | Six Degrees Technology Group Limited | 14/01/2020 |
| 01243 282 | Six Degrees Technology Group Limited | 14/01/2020 |
| 01243 284 | Six Degrees Technology Group Limited | 14/01/2020 |
| 01243 29 | FleXtel Limited | 19/10/2005 |
| 01243 300 | IP Wholesale Limited | 01/06/2017 |
| 01243 323 | Digital Space Group Limited | 12/04/2016 |
| 01243 324 | Digital Space Group Limited | 12/04/2016 |
| 01243 33 | GCI Network Solutions Ltd | 20/04/2017 |
| 01243 340 | Digitech Solutions Global Limited | 22/06/2012 |
| 01243 341 | Sky UK Limited | 10/09/2019 |
| 01243 342 | 24 SEVEN CLOUD COMMUNICATIONS LTD | 17/01/2020 |
| 01243 343 | SiPalto Ltd | 05/11/2019 |
| 01243 344 | Dial 9 Communications Limited | 09/12/2019 |
| 01243 345 | BT | 26/11/2019 |
| 01243 346 | DIDWW Ireland Limited | 27/01/2020 |
| 01243 347 | Orbital Net Limited | 19/08/2020 |
| 01243 348 | Belgacom International Carrier Services SA | 14/10/2019 |
| 01243 349 | Gamma Telecom Holdings Ltd | 12/11/2019 |
| 01243 37 | BT | 15/07/1994 |
| 01243 38 | BT | 15/07/1994 |
| 01243 39 | TGL Services (UK) Ltd | 02/02/2015 |
| 01243 410 | Vodafone Ltd (C&W) | 03/10/2013 |
| 01243 411 | Vodafone Ltd (C&W) | 03/10/2013 |
| 01243 412 | Vodafone Ltd (C&W) | 03/10/2013 |
| 01243 413 | Vodafone Ltd (C&W) | 03/10/2013 |
| 01243 414 | Vodafone Ltd (C&W) | 03/10/2013 |
| 01243 415 | Vodafone Ltd (C&W) | 03/10/2013 |
| 01243 416 | Vodafone Ltd (C&W) | 03/10/2013 |
| 01243 42 | IV Response Limited | 04/07/2005 |
| 01243 43 | Virgin Media Limited | 24/01/1995 |
| 01243 441 | Virgin Media Limited | 27/06/2012 |
| 01243 442 | Virgin Media Limited | 27/06/2012 |
| 01243 459 | Virgin Media Limited | 27/06/2012 |
| 01243 460 | Media Hawk Ltd | 02/12/2015 |
| 01243 462 | Media Hawk Ltd | 28/09/2016 |
| 01243 463 | Adepteo Limited | 16/01/2017 |
| 01243 464 | Mintaka Limited | 25/11/2016 |
| 01243 465 | Sky UK Limited | 10/06/2016 |
| 01243 467 | I.T Communications Limited | 29/11/2016 |
| 01243 468 | IOVOX Limited | 28/03/2017 |
| 01243 469 | Number Services Ltd. | 22/11/2018 |
| 01243 487 | Spitfire Network Services Limited | 21/07/2011 |
| 01243 495 | GTT-EMEA LTD | 14/10/2021 |
| 01243 50 | Barritel Limited | 09/03/2006 |
| 01243 51 | BT | 15/07/1994 |
| 01243 52 | BT | 15/07/1994 |
| 01243 53 | BT | 15/07/1994 |
| 01243 54 | BT | 15/07/1994 |
| 01243 55 | BT | 15/07/1994 |
| 01243 56 | TelNG Limited | 26/02/2007 |
| 01243 57 | BT | 15/07/1994 |
| 01243 58 | BT | 15/07/1994 |
| 01243 59 | Localphone Limited | 24/04/2007 |
| 01243 60 | BT | 15/07/1994 |
| 01243 61 | Verizon UK Limited | 03/04/2007 |
| 01243 62 | Vodafone Ltd (C&W) | 03/10/2013 |
| 01243 63 | TTNC Limited | 11/11/2013 |
| 01243 64 | BT | 15/07/1994 |
| 01243 65 | Alphatalk Limited | 31/01/2014 |
| 01243 666 | Served Up Limited | 01/03/2013 |
| 01243 667 | Served Up Limited | 01/03/2013 |
| 01243 67 | BT | 15/07/1994 |
| 01243 680 | Voiceflex Limited | 04/09/2007 |
| 01243 681 | TalkTalk Communications Limited | 12/02/2013 |
| 01243 682 | VoIP-Un Limited | 26/10/2007 |
| 01243 683 | Digital Space Group Limited | 15/03/2016 |
| 01243 684 | Voxbone SA | 10/12/2007 |
| 01243 685 | Digital Mail Limited | 29/04/2008 |
| 01243 686 | Digital Space Group Limited | 29/11/2007 |
| 01243 687 | IPV6 Limited | 27/01/2009 |
| 01243 689 | (AQ) LIMITED | 17/10/2011 |
| 01243 696 | TalkTalk Communications Limited | 31/08/2011 |
| 01243 697 | TalkTalk Communications Limited | 31/08/2011 |
| 01243 698 | TalkTalk Communications Limited | 31/08/2011 |
| 01243 699 | TalkTalk Communications Limited | 31/08/2011 |
| 01243 70 | Redcentric Solutions Limited | 05/06/2015 |
| 01243 710 | Nodemax Limited | 15/07/2008 |
| 01243 712 | Mars Communications Limited | 04/02/2009 |
| 01243 713 | Commi Holdings Limited | 21/11/2016 |
| 01243 714 | Solutios Limited | 27/08/2008 |
| 01243 715 | Andrews & Arnold (Numbers) Ltd | 26/02/2009 |
| 01243 716 | Telecom2 Limited | 11/09/2009 |
| 01243 717 | Affiniti Integrated Solutions Limited | 12/11/2007 |
| 01243 719 | Invade International Ltd | 12/01/2016 |
| 01243 720 | Lumen Technologies UK Limited | 25/07/2011 |
| 01243 723 | Lumen Technologies UK Limited | 25/07/2011 |
| 01243 729 | Lumen Technologies UK Limited | 25/07/2011 |
| 01243 73 | Syntec Limited | 21/12/2004 |
| 01243 75 | BT | 15/07/1994 |
| 01243 760 | Telecoms World PLC | 09/03/2009 |
| 01243 761 | TeleWare Group PLC | 21/02/2013 |
| 01243 762 | Chess Limited | 06/04/2018 |
| 01243 763 | Sky UK Limited | 21/06/2013 |
| 01243 764 | Vectone Mobile Limited | 29/06/2009 |
| 01243 765 | Andrews & Arnold Ltd | 20/08/2007 |
| 01243 766 | Net-Work Internet Ltd | 28/01/2008 |
| 01243 767 | Inet Telecoms Ltd (Voipfone) | 27/02/2009 |
| 01243 768 | CFL Communications Ltd | 07/07/2009 |
| 01243 769 | Nationwide Telephone Assistance Ltd | 01/10/2007 |
| 01243 77 | BT | 15/07/1994 |
| 01243 78 | BT | 15/07/1994 |
| 01243 79 | BT | 30/04/1996 |
| 01243 80 | Citrus Telecommunications Ltd | 08/03/2006 |
| 01243 81 | BT | 15/07/1994 |
| 01243 82 | BT | 15/07/1994 |
| 01243 83 | BT | 15/07/1994 |
| 01243 84 | BT | 15/07/1994 |
| 01243 85 | BT | 21/03/1995 |
| 01243 86 | BT | 15/07/1994 |
| 01243 87 | BT | 16/02/1999 |
| 01243 880 | Magrathea Telecommunications Limited | 16/11/2011 |
| 01243 881 | Magrathea Telecommunications Limited | 16/11/2011 |
| 01243 882 | Magrathea Telecommunications Limited | 16/11/2011 |
| 01243 884 | Magrathea Telecommunications Limited | 16/11/2011 |
| 01243 885 | Magrathea Telecommunications Limited | 16/11/2011 |
| 01243 887 | Magrathea Telecommunications Limited | 16/11/2011 |
| 01243 888 | Magrathea Telecommunications Limited | 16/11/2011 |
| 01243 889 | Magrathea Telecommunications Limited | 17/11/2011 |
| 01243 890 | Resilient PLC | 09/09/2011 |
| 01243 899 | Resilient PLC | 09/09/2011 |
| 01243 901 | Nexus Telecommunications Limited | 25/09/2009 |
| 01243 904 | I-NET COMMUNICATIONS GROUP PLC | 15/01/2010 |
| 01243 907 | Atomstream Limited | 25/02/2010 |
| 01243 908 | Buzz Networks Limited | 01/03/2010 |
| 01243 909 | E164 Ltd | 22/03/2010 |
| 01243 910 | Digitech Solutions Global Limited | 23/04/2010 |
| 01243 911 | Suretec Systems Ltd | 29/04/2010 |
| 01243 912 | Calltracks Limited | 19/09/2013 |
| 01243 913 | Windsor Telecom Ltd | 19/07/2010 |
| 01243 914 | Core Telecom Limited | 05/08/2010 |
| 01243 915 | VoiceHost Limited | 26/08/2010 |
| 01243 916 | Numbergroup Utilities Ltd | 03/12/2010 |
| 01243 919 | Invosys Limited | 26/01/2012 |
| 01243 920 | Sky UK Limited | 21/06/2013 |
| 01243 921 | Hello Telecom (UK) Limited | 14/04/2011 |
| 01243 923 | Nexbridge Communications Limited | 06/03/2012 |
| 01243 924 | Orbtalk Limited | 11/07/2011 |
| 01243 925 | Minotaur Telecom Limited | 31/01/2013 |
| 01243 926 | Sky UK Limited | 24/06/2013 |
| 01243 927 | Media Hawk Ltd | 10/04/2013 |
| 01243 928 | Affiniti Integrated Solutions Limited | 19/11/2013 |
| 01243 929 | iHub 2 Limited | 18/05/2016 |
| 01243 930 | Sky UK Limited | 20/06/2013 |
| 01243 931 | TalkTalk Communications Limited | 29/11/2013 |
| 01243 932 | Orange Business Holdings UK Limited | 16/01/2013 |
| 01243 933 | Kalnet4U Ltd | 08/05/2013 |
| 01243 934 | Content Guru Limited | 29/08/2013 |
| 01243 935 | Redwood Technologies Ltd | 15/11/2018 |
| 01243 936 | Sky UK Limited | 13/01/2014 |
| 01243 937 | Sky UK Limited | 13/01/2014 |
| 01243 938 | XoverX Ltd | 01/05/2013 |
| 01243 939 | Colt Technology Services | 30/01/2013 |
| 01243 940 | BT | 05/02/2014 |
| 01243 941 | TalkTalk Communications Limited | 09/09/2014 |
| 01243 942 | Vonage Limited | 27/01/2015 |
| 01243 943 | YayYay Limited | 23/04/2015 |
| 01243 944 | Lanonyx Telecom Limited | 03/03/2015 |
| 01243 945 | Sky UK Limited | 19/05/2015 |
| 01243 946 | M247 Ltd | 29/05/2015 |
| 01243 948 | Sky UK Limited | 07/09/2015 |
| 01243 949 | Internet of Things Limited | 13/08/2018 |
| 01243 950 | TalkTalk Communications Limited | 03/07/2017 |
| 01243 951 | Sky UK Limited | 08/06/2017 |
| 01243 952 | Gamma Telecom Holdings Ltd | 05/12/2017 |
| 01243 953 | Entanet International Ltd | 12/12/2017 |
| 01243 954 | Telappliant Ltd | 05/04/2018 |
| 01243 955 | Fuse 2 Communications Ltd | 03/07/2017 |
| 01243 956 | BT | 02/10/2018 |
| 01243 957 | Gamma Telecom Holdings Ltd | 24/04/2018 |
| 01243 958 | Gamma Telecom Holdings Ltd | 29/10/2018 |
| 01243 959 | Zapappi Ltd | 05/01/2018 |
| 01243 960 | Club Communications Ltd | 18/05/2018 |
| 01243 961 | TalkTalk Communications Limited | 21/11/2018 |
| 01243 962 | ICUK Computing Services Limited | 12/08/2019 |
| 01243 963 | Colt Technology Services | 24/08/2018 |
| 01243 964 | Gamma Telecom Holdings Ltd | 06/06/2019 |
| 01243 965 | VOXYONDER NETWORK SERVICES UK LTD | 10/09/2020 |
| 01243 966 | Affiniti Integrated Solutions Limited | 27/05/2020 |
| 01243 967 | BT | 13/10/2020 |
| 01243 968 | Sky UK Limited | 22/12/2020 |
| 01243 974 | Gamma Telecom Holdings Ltd | 19/08/2020 |
| 01243 976 | Gamma Telecom Holdings Ltd | 23/06/2021 |
| 01243 977 | Mi Telecom Limited | 03/07/2020 |
| 01243 978 | Gamma Telecom Holdings Ltd | 11/03/2021 |
| 01243 979 | Gamma Telecom Holdings Ltd | 20/04/2020 |