How do I get Distinctive Ringing for external versus internal calls on my Cisco IP Phone?
A. Distinctive Ringing is a feature that is available on Cisco CallManager 3.0 and later when you use Skinny Gateways such as the DT24+ or the 6608 T-1 blade. However, this functionality is not available until release 3.1.2c with use of an H.323 gateway. In order to enable Distinctive Ringing, you must set the service parameter H323NetworkLocationOffNet to True.