have an access list blocking tcp port 2000 on a switchport to force the phone into srst mode. Voice GW is still under mgcp / cm control. Phone says "opening x.x.x.x" IP address of VGW. Has anyone ever done this
Blocking port 2000 at the switchport means that SCCP traffic can also not get from the phone to the SRST gateway. You'll need to block SCCP across the WAN.