EXHIBIT 21 SUBSIDIARIES OF NTL INCORPORATED All of the corporations listed below were organized in the United Kingdom. CableTel Cardiff Ltd. CableTel Central Hertfordshire Limited CableTel Glasgow CableTel Hertfordshire Limited CableTel Herts and Beds Limited CableTel Investments Limited CableTel Kirklees CableTel Limited CableTel Newport CableTel North Bedfordshire Limited CableTel Northern Ireland Limited CableTel Scotland Ltd. CableTel South Wales Ltd. CableTel Surrey and Hampshire Limited CableTel Telecom Supplies Limited CableTel (UK) Limited CableTel West Glamorgan Ltd. CableTel West Riding Limited Chamber Online Limited Columbia Management Limited Digital Television Network Limited DTELS Limited Enablis Limited Metro Hertfordshire Limited Metro South Wales Limited National Transcommunications Limited NTL Group Limited NTL Insurance Limited NTL Internet Limited NTL Investment Holdings Limited NTL Limited NTL Networks Limited NTL Trustees Limited Prospectre Limited Secure Backup Systems Limited All of the corporations listed below were incorporated in Delaware: CableTel Programming, Inc. CableTel Ventures Limited Cellular Paging, Inc. L.D. Data, Inc. NTL International Services, Inc. NTL (UK) Group, Inc. OCOM Corporation OCOM New York, Inc. OCOM Pennsylvania, Inc.