When integrating the ShoreTel PRIs into a Avaya (formerly Nortel) PBX you will have to create a T1 Crossover cable for voice.
This can be done simply by using a patch cable and a RJ45/DB15 adapter. When you go the route of the adapter you will have to pin out the cables in the RJ45/DB15 adapter.
The RJ45/DB15 adapter will be a Female adapter that will plug into the DB15M cable coming from the Nortel PBX. Make sure that you do have the cable that terminates in a DB15M so that the adapter will work.
In order to not only connect but to create a Cross Over cable, means you have to flip the pairs for Trans/Receive.
The RJ45 adapter will come with pins that are coloured and the colours do reflect a certain order:
Blue –> 1
Orange –> 2
Black –> 3
Red –> 4
Green –> 5
Yellow –> 6
Brown -> 7
White –> 8
In the DB15F adapter you will want to pin out the adapter in the following way:
Blue –> goes into 9
Orange –> goes into 1
Red –> goes into 11
Green –> goes into 3
Therefore the adapter should only have pins in 1,3,9 and 11. I normally leave the other cables bunched into the adapter.