EXHIBIT 21.1 Subsidiaries of the Registrant EXHIBIT 21.1 Subsidiaries of the Registrant State of Doing Business Name of Subsidiary Incorporation As - ---------------------------------------------------------------------------------------- Bay Area Teleport, Inc. Delaware -- Communications Buying Group, Inc. Ohio -- DataChoice Network Services, L.L.C. Nevada -- DownNorth, Inc. (formerly known as UpSouth Corporation) Georgia -- ICG 161, L.P. Delaware -- ICG Access Services - Southeast, Inc. (formerly known as PrivaCom, Inc.) Delaware -- ICG Canadian Acquisition, Inc. Delaware -- ICG ChoiceCom, L.P. (formerly known as CSW/ICG ChoiceCom, L.P.) Delaware -- ICG ChoiceCom Management, LLC (formerly known as Southwest TeleChoice Management, LLC and CSW/ICG ChoiceCom Management, LLC) Delaware -- ICG Corporate Headquarters, L.L.C. Colorado -- ICG Enhanced Services, Inc. Colorado -- ICG Equipment, Inc. Colorado -- ICG Funding, LLC Delaware -- ICG Holdings, Inc. (formerly known as IntelCom Group (U.S.A.), Inc.) Colorado -- ICG Holdings (Canada) Co. Nova Scotia -- ICG Mountain View, Inc. Colorado -- ICG Ohio LINX, Inc. (formerly known as Ohio Local Interconnection Network Exchange Co.) Ohio -- ICG NetAhead, Inc. (formerly known as NETCOM On-Line Communication Services, Inc. and ICG PST, Inc.) Delaware -- ICG Services, Inc. Delaware -- ICG Telecom Canada, Inc. Federal Canadian -- ICG Telecom Group, Inc. ICG Telecom Group, Inc. (formerly known as ICG Access Services, Inc.) Colorado -- ICG Telecom Group of Virginia, Inc. Virginia -- ICG Telecom of San Diego, L.P. (formerly known as Linkatel of California, L.P.) California -- ICG Tevis, Inc. Delaware -- NikoNet, LLC Georgia -- PTI Harbor Bay, Inc. Washington -- TransAmerican Cable, Inc. Kentucky MidAmerican Cable Zycom Corporation (formerly known as Camber Sports, Inc.) Alberta, Canada -- Zycom Corporation Texas -- Zycom Network Services, Inc. (formerly known as Travel Phone, Inc.) Texas --