Does He hear the ringing on the handset or on the unit ? Hnadset or speaker ?
Does He get the person calling ( audio ) ?
When the call comes in , the NBX sends a packet to the tel to say ring . When yuio pick up the call , the ttel sends a packet back to say off hook . It sounds like possibly one of two things :
1. The tel may be defective . Have you tried swapping out the telephone with a known good one ?
2. Sometimes over the network , if changes are made , the packet never gets back to the NBX . You may have a network condition going on .
It sounds like a Tel to me for now ( need more info ) .