Symptom:
There is one-way audio experienced when a secure call is placed between a 6945 phone & jabber. 

In this situation the phone is not able to hear the jabber user however the jabber user can hear the phone user, this is experienced on a call that lasts for around 15-20 mins.

In the phone console logs you would see the following

1329 ERR 15:24:09.238719 ms-SRTPIF.srtcpifUnprotect: failed with error code 7, session 25 
1330 ERR 15:24:09.238819 ms-RTCP-rtcpm_rcvPacket srtpUnprotect error 
1331 NOT 15:24:09.238905 ms-SRTPIF.srtpifDealloc, session 25

5364 ERR 08:28:50.865511 ms-RTPPKTMGR Rx stream block 7: Pkts discard decryption error

Conditions:
Secure call between 6945 phone & jabber that lasts for 15-20 mins