I think You are looking to support H.248 which is an ITU recommendation that
defines "Gateway Control Protocol." In many ways, H.248 builds on and
extends MGCP.
currently 2800 series router do not support H.248 protocol.
Looks like products such as PGW 2200 Softswitch support H.248 protocol.
Also,Cisco has a high end Media Gateway that supports H.248 which is (MGX
8800).