I have a handful of remotely connected Nortel IP phones that intermittently lose their "Feature Keys" however they retain their voice capabilities. Resetting the phone by pbx or recyling does not fix the problem. Only by going into the signaling server and resetting the features for that specific phone seems to do the trick. From an IP perspective what criteria must be met to ensure proper operation of the phone feature keys? Is there another signaling protocol that must be given a certain level of qos outside of the call signaling and voice streams that controls these features? I'd appreciate any help.

Computers & Internet - Nortel - i2004 IP Phone