b410p to b410p

I’ve been told I can do this but for the life of me I can’t get it to work. We currently have asterisk 1.2.14 running misdn and a b410p digium isdn card to connect to 3 onramp2 ISDN channels. that works fine.

I want to set up a second system that is a mirror of the first so that we can make changes on and test before rolling them out to a live system. I want the second system to be connected to port 4 of the b410p card on the live system so it can make and recieve calls via the ISDN channels without disconnecting cables and swapping to the test box and then back again.

I’ve tried setting the jumper on port 4 of the live system to NT and port 1 on the test system to TE and all combinations te_ptp te_ptmp nt_ptp nt_ptmp but I can’t get layer2 to come up. Can someone give me a run down of what is needed to connect the 2 systems together so I can ring extensions and outside lines between the 2 systems.