Cannot hear caller sporadically - several T28

[dcfindlay]

Two different T28's at different sites have had this problem in the last year. Both phones were in service for over a year before the problem started. The user started being unable to hear callers, frequently but not always. And only on the handset. The call works fine when put on speaker.

I've replaced the handset and handset cord. No change. Only replacing the phone cured the problem.

The firmware was not changed since installation. Neither was the network. All other T28's on those two networks are working fine. They were in regular offices with heat and A/C.

Has this been see before? Corrosion in the jack perhaps? Or a failing amplifier?

[Yealink_Michael]

hi

for this issue, it is suggest to change the handset or the spiral line and try again , if the issue still exist , then it is suggest to upgrade to the last firmware, firmware download link :

http://support.yealink.com/documentFront...umentId=16

firmware number : 2.73.0.50.zip

a factory reset after upgrade is required ,

if issue still exist , then please send the trace file for future analysis to support@yealink.com

trace file including pcap file, config bin and syslog file , for how to get them , please refer to the FAQ below:
http://forum.yealink.com/forum/showthread.php?tid=1319