I have one T1 circuit for TDM voice traffic. It supports in/out (can recevie call from provider and send the call to providers). How do I send the call to provider always from channel 23rd? how to config the routers?
Usually providers send calls on the lowest channel. You can check that with "debug isdn q931".
However the ISDN protocol is made so that call will never collide, so you don't have to worry about.