One-Way audio after on hold

[leemason]

I am having exactly the same problem with a site I have recently installed with Yealink T20P handsets. Some have been upgraded to the latest firmware downloaded about 1 week ago with no success. When a call is put on hold and retrieved the caller experiences one way audio. I have hundreds of other Yealink handsets installed mostly T28/T26/T4x and they all seem to be fine. As above this is running with Asterisk (11.17.1). I also have a number of customers with other handsets (Snom, Aastra, Gigaset) and none of these are having the same sort of problem.

The handsets had a similar problem with call transfer also. When an attended transfer was performed and the extension being transferred to did not want to take the call is was not possible to get the call back from the transfer. I got around this by reprogramming the transfer key to use the Asterisk feature code (*2) rather than the phone based transfer.