A modular unit with different numbers of keys (based on the specific expansion module) can be attached to 16-key 2xxx digital phones, specific 39xx digital desk phones, and most UNIStim IP phones. Note that a specific station may have more than one possible choice of key expansion module, but some modules are limited to a subset of the stations supporting the added modules.

The extra keys can be assigned to any combination of lines and features. You can typically add more than one expansion modules to a single telephone, providing an increase in line/feature keys.

You will need a separate footstand for the module(s). The modules do not use the same base as the station itself.

The Key Expansion Module connects to the telephone through a ribbon cable running from the base of the telephone. It is physically connected to the telephone by the footstand, which attaches to the footstand of the station.

For more information about the specific expansion modules supported on Device Adapter, see the user guides for the supported endpoints.