Patent ID: 7593410

Claim:
A call control system in a communication network, the system comprising: a plurality of network terminators to respectively connect to a plurality of subscriber terminals; and a subscriber line concentrator to establish and terminate, using a call control function, VCs (Virtual Connections) with the plurality of network terminators and couple to a switching apparatus of the network through a UNI (User-Network Interface), where the subscriber line concentrator performs a protocol conversion between a first protocol stack used between the subscriber line concentrator and the switching apparatus and a second protocol stack used between the subscriber line concentrator and the plurality of network terminators, where the plurality of network terminators performs a protocol conversion between the second protocol stack and a third protocol stack used between the plurality of network terminators and the plurality of subscriber terminals, where the first protocol stack differs from the second protocol stack and the second protocol stack differs from the third protocol stack, and where at least one layer of the first, second, and third protocol stacks uses a same protocol.