Excessive bandwidth consumed when using Asterisk

We’re setting up a voip-over-satellite network here. We have AudioCodes FXS at the remote locations and an AudioCodes FXO at the hub location (connected to PSTN).

We originally were making connections directly between the FXO and FXS, and this worked fine. When we would make an outgoing call from the FXS, we’de see 35 packets per second (3 KBytes/second) in each direction while the call was in progress.

Now we’ve switched to using Asterisk as PBX/call router, because the FXO doesn’t support enough extensions (we have 80 remotes). However now when I make an outgoing call, we see 48 packets/sec (11 KBytes/sec) in each direction. This completely consumes all available bandwidth for the outgoing link, and we cannot make a second call.

We have “canreinvite=yes” in sip.conf for each user, my understanding was that this would cause * to set up a direct connection between the FXO/FXS once the connection was made??

What is causing all of this extra traffic?? This is not good for our product…