Intermittent "No Response" on Incoming Calls

[voyant]

3cx system version 15.5.0 running mostly Grandstream GXP2160 phones.

This happens intermittently, maybe around 1 in 5 times, maybe a little less often. When receiving an incoming call, the appropriate BLFs for the phone lines light up and the display on the phone says "ringing." The phone is set to automatically answer the call when the handset is picked up out of the cradle. As soon as the handset is picked up to answer the call, though, the display changes and says "No Response." The call is not picked up, and the phone keeps ringing.

Have tried physically switching phones with no changes, so it appears that the hardware is ok. Is there a wrong setting somewhere? if so, why does this happen only sometimes and not all the time? Anybody else have this problem and find the fix for it?

 

[leejor]

Are the sets local or remote? If remote...STUN, or SBC? Has this always been this way? Did it start after a version change? Change in hardware, (set) firmware upgrade? Are the sets using the most recent (3CX approved) firmware?

 

[voyant]

The sets are local and on the latest firmware. These intermittent problems have been around from the start. I had originally thought it was operator error - pushing the wrong button or not properly hanging up the handset. However i witnessed this problem personally when I called the company from my cell phone while standing next to the person answering the phone.

Any ideas? The client says they have become "used to it," but that's not really acceptable.

 

[cobaltit]

Have you checked the activity log to see what it shows when this happens?