My environment: UC Manager 184.108.40.20600-3
For some reason you might want to disable call waiting on your 7900 series IP phone. One of the reason is you want to test out the Call Forward Busy easily by only making 2 calls to a phone. Go to the DN settings and make the “Maximum number of calls” and “Busy Trigger”to “1”. Your phone will now only accept 1 call!