Calls Drop after about 2 minutes

I’ve finally gotten Asterisk 11 and FreePbx 2.11 installed on my Centos7 system.
Everything is running fine so far it seems.
I’ve noticed a dropped call on a call I made this morning.
I’m also getting an error message with the Asterisk CLI and was wondering if somebody might have an idea what the issue might be or how to fix it?
The error is:

[2014-09-11 09:53:35] WARNING[20415]: chan_sip.c:4024 retrans_pkt: Retransmission timeout reached on transmission [email protected] for seqno 2 (Critical Response) – See

I’ve done some investigation and read the article from btw. Maybe some kind of NAT issue.

At 2 miniutes, it is probably a case of broken session timer support. (Two minutes is too long for NAT problems on the ACK, broken re-invite support, or broken connected line update support.)