How to determine D125B compatibility with the D7112.

 Can the D125B be Used to Power 2 Wire Smokes on the D7112?

Yes, see technogram number (73-06116-000-C) 1993 (attached).
Listings and Approvals
Underwriters Laboratories lists the D7112 ControVCommunicator as a Digital Alarm Communicator Transmitter (DACT) for:
NFPA 71 Central Station, NFPA 72 Chapter 6 Local, NFPA 72 Chapter 8 Remote Station, NFPA 74 Household Fire Warning.
The D7112 also has the following Approvals: CSFM and NYC-MEA (formerly NYC-BSA).