Norstar C8 Caller ID (NT8B88FB) - Adds Caller ID capability to your Norstar 8x24 phone system. When you subscribe to Caller ID service from your phone company, this module puts the Caller's information on your Norstar phone display. Requires a 8x24 with DR5 or DR5.1 software. Not compatible with older versions of software. This unit provides Caller ID information for the 8 trunks pre-installed in your 8x24. It does not provided Caller ID for trunk cards that are inside trunk module cabinets (add-ons). For Caller ID services on trunk modules, you must use Caller ID trunk cards.