You will always have volume problems when conferencing two CO lines through a system.

There is usually a 3-5Db loss from the original inbound call, a 1-2Db loss through the sytem and then another 3-5Db loss back out to the CO and whatever loss from that on out to the terminating end! (Remember a 3Db loss is equal to half the volume)

With the bigger digital systems using PRI or plain T-1 inbound and outbound trunks there is still loss but it is so negligible the human ear can't detect it.

The absolute best way to handle these off site call transfers is to use the CO's centerex transfer service and the calls are transferd by the CO and results in no loss and not taking up two lines.


DJ