I have two Philips PBX's connected via Cisco 2651 routers - ISDN PRI on one side and ISDN BRI on the other side. When I make modem calls to the other side, the connected speed trails down to 300 baud. I know I need to set up modem pass-thru, but it seems like it is only supported on the AS5300. Is there a way to get around the problem on a 2600 router?
