Hi
You configuration seems to be correct, however, I don't know what you have set in NACDS to allow traffic with cat 3.
I suggest you to set TRAF=03151515 before to be sure that your ISDN phone is working.
Mainly the ISDN phone take power from the bus, so if you have some screen on it, it should light.
Otherwise, you have a wrong connection.
When you say that it don't work, what kind of message do you have from DTS? BLOCKED or BARRED?