ICE negotiation fails after endpoint has been idle for long time

[bennylp]

Ravin Suri reported:

3. I have seen some instances where after many hours of running pjsua in an

idle mode, it will not be able to make calls due to ICE negotiation failing.
On quitting pjsua and restarting it, a call to the same destinations is
successful.

This is the sequence of steps:

• start pjsua on both ends
• make a call from one to another -- this works fine, ICE neg succeeds

and call is ok.

• hang up call after a few minutes
• let the pjsua's keep running for say, 8 hours
• try to make the same call again to the other pjsua
• ICE negotiation fails
• shut and restart caller pjsua
• call other pjsua
• ICE works and call is made successfully