AT&T RELEASE 2 - Manual (Page 40)

You can also add accessory equipment to the system that plugs into the
control unit. You can add a data collector and printer to your system to
collect data on calls and print Call Reports. The 450F adapter allows the data
collector to share port 19 with the Busy Buster feature. Refer to the MERLIN
Plus System Manual for more information on Busy Buster. See Figure 28.
You may also add a Basic Telephone and Modem Interface (BTMI) in order to
connect a basic telephone, dialing modem, or facsimile machine to the
system. See Figure 29.
FIGURE 28 MERLIN Plus system data collector and printer.
36 Step 5: Adding Accessories