After analyze, when i perform a call over a VPN the bandwith used is twice the bandwith used the same configuration using an ISDN link. On my configuration i use on one side an ASA 5520 ans on the other side an 3640. The phoneset use H323 protocol. Using the codec G729 the bandwith is 50 K over the VPN ans 25 over the ISDN. Using 711 the bandwidth is 200 K over the VPN and 100 K over the ISDN. I know than encryption add overhead but twice it seem very higth.
Do you have an idea.