How much do you know about the Avaya Magix? Magix is able to be Switch-to-Switch networked using a T1 or PRI through UDP same in the older Definity switches such as SCC, ESCC and MCC up to I think Release 11. UDP (Universal Dial-Plan) unlike IPO UDP is done through a minimum of a 4 digit extension dial plan on the Magix side and the receiving side (the IPO) unless translations can fix that!? I say try it, if the extensions need to be less than 4 on the IPO side. Otherwise, stick to the needs of the legacy equipment needs of 4. You will have to emulate a E&M Tie for all channels and use wink-start. The dial plan like SCN in the IPO must have unique extensions however not to the extent the IPO needs in all areas such as line numbering, trunk groups etc, since the Magix dial 9 is related to the Main Trunk Group of 70. I say, get started, and I'll watch for your issues, if any.
This can be fun!
Lord