Retransmission timeout reached

getting this about 3 times a day and the call will disconnect. Very simple setup. Router is not managed by me but they said it was mapped 1 to 1 with external ip to my freepbx distro box at 10.0.0.1

not sure if i need to use nat=yes. also I am using Vitelity. There is an option for the account specifying if the account needs nat. It is labeled as yes.

inbound peer setting are as follows:

secret=xxxxxx
username=xxxxxx
host=inbound25.vitelity.net
type=friend
dtmfmode=auto
context=from-trunk
disallow=all
allow=ulaw
insecure=very
nat=yes

This was used as Vitelitys example for trixbox. Seems to have been working for nearly a year and a half and for some weird reason they are now telling me about the issue. Another big boo boo on my part is I am running Freepbx distro 1.1100.211.63-3 which was beta at the time but seemed to run rock solid. This is my bad and I do want to upgrade it to the latest stable but I don’t know what the repercussions are going to be. I can’t take them down so i just might make a new server, upgrade the old then put it back. That’s another issue. Anyone have ideas on the dropped calls? Again they only happen about 2 times a day on a system that is doing about 40k minutes a month. Thanks for any advice.

Asterisk Sip Settings are

Nat Yes
IP configuration Public IP.