According to
this chart, the Call Pilot 100 should work with a 3x8 DR 5.1.
The downside to the 3x8 is, no hunt groups, 2 digit DN's, full capacity on the line(s) side, and no CID.
The upside is, it's cheaper
If you can talk them into a CICS, they will thank you in the long run. :thumb: