I have had an intermittent issue where users attempt to answer a call, but the device(spa504g) freezes and the lcd gets stuck "Answering". The phone becomes unresponsive to any button presses; even after considerable patience. The call is eventually dropped, and if we're lucky the customer calls back. The only solution is to unplug the power and repower the device.
On the server side, the phone often remains registered for sometime even showing that it is still on a call. I think after about 15 minutes the registration drops. So if I attempt to repower the phone before it unregisters, it will seem to register fine but will not actually ring on any inbound calls. Most of the time I've resorted to restarting services on the server which effectively brings the system down, even if only for a minute.
I'm using 3cx phone system. Our server is collocated so all extensions are remote. Aside from this, we have no other issues
We have 5 end points at this location all SPA504g with 7.5.4 firmware. We have low call volume and I'm usually the first guy to take calls 90% of the time. But I have swapped out phones and confirm that it has happened on more than one device, even on previous firmwares.
I can't reproduce the issue. It has happened about 5 times this week, but hadn't happened in over a couple of months prior to this week.
I have experienced the issue ever since we went live with the system. So basically since everything was new out of the box.
I have created a support ticket with 3cx, providing syslogs for the phones, logs from the phone system, and wireshark pcap on the server. They say there is no problem on the server and that it is probably a phone/networking issue.
