Multitech CallFinder CF220-DID Cabling Manual page 11

Identify CallFinder's Extension Ports (FXS/FXO) for Later
Hookup
Caution: You must wait until after the CallFinder software has
been configured before connecting the cables
between the CallFinder's Extension (FXS/FXO) Ports
and the PBX. Because the CallFinder and the PBX
can both supply battery power, the cable connections
must be done properly. Otherwise equipment
damage could occur.
Before making connections to the CallFinder Extension
(FXS/FXO) channels, you must know the type of PBX port to
which each CallFinder port will be connected and set the
"Extension Port" field in the CallFinder Channel Configuration
screen appropriately.
When connecting to a PBX Station Port,
set the CallFinder channel to FXO.
When connecting to a PBX Trunk Port,
set the CallFinder channel to FXS.
When the Channel Configuration | Extension Port software
field has been set properly for both CallFinder channels, you can
proceed to connect the cable between each of the CallFinder's
FXS/FXO ports and the corresponding PBX port.
MultiTech Systems, Inc.
CallFinder Cabling Guide
11