When extensions are a part of multiple ring groups it is sometimes helpful to know which ring group the calls is coming from.

To enable this feature we have the distinctive CID feature (Path: Settings -> PBX -> General -> Preferences -> Distinctive Caller ID). 

Iif you enable this feature, and for example you have a ring group with Ring Group number 6201, and Ring Group name as SALES, when the incoming call (Caller is 123456789) to this ring group, the agent phone will display as below:

Caller ID Name:  6201 (SALES)

Caller ID Number:  123456789