there are two ways to control simultaneity on the channels
1. use the simultaneous access variable in the customer record
2. use the call-limit parameter in the sip.conf configuration of the peer
call-limit = number : Number of simultaneous calls through this user/peer.
http://www.voip-info.org/wiki/view/Aste ... ominglimit
the virtual pri interfaces to the server thru a channel and you would use the call-limit in the sip channel to limit the amount of simultaneous calls that can actually go over the PRI. so if you set its call-limit to 6 you would get 6 calls in/out over the PRI on the 7th call you would be told that the channel is unavailable