Symptom:
One way audio for secure call via 3G under low bandwidth intermittently. Can't hear remote side audio,but remote side can hear voice from my side.

Conditions:
Steps to reproduce:
1. Set iPhone device to secure mode
2. Login jabber via 3G, the bandwidth is low
3. Call by PSTN/Meeting call back/ jabber client
4. Sign out and resign in via corp-wifi or home wifi
5. Start call again

Expect Result:
Both sides hear audio clearly in the call conversation. 

Actual Result:
Sometimes one way audio for secure call via 3G . switch network, call works well again.