I have a client that was using thier Merlin Magix PBX to handle the inbound T1. The CSU\DSU failed and they were unable to obtain a new card that could support it. I am installing a 2600 router with a 1MFT-T1 card and the original wic 1T serial card that connected to the PBX. I have the data connected and running fine on channels 1 -12 from the T1 on the controller card, but I am not sure how to configure the phone channels on 13-23 to use the wic 1T serial card to connect and talk to the PBX??