I would like to put together a solution to eliminate our T1 circuits used just for voice and consolidate to our IP network. I have tried Circuit Emulation cards and have not been happy with the results (mainly echo problems). I am interested in trying to set up two routers as voice gateways between the two PBXs. From the Cisco docs I have read, using a VWIC-2MFT-T1 I should be able to configure it as an E&M tie line and then transfer it across the IP network. Do I also need PVDSPs? Has anyone done this and have any recommendations. The two PBXs are connected with tie lines now using service provider T1s.