I would like to add an update to this and maybe someone has some other suggestions - It does look like that FS is disconnecting the call with cause code 31  [NORMAL_UNSPECIFIED] I did not notice the time stamp difference on the Bye when I first looked at the log's

The basis of the issue still stands a 491 Results in the B-Leg being disconnected

On Aug 24, 2012, at 12:53 PM, Mike Burlingame <mike.burlingame@me.com> wrote:

We are seeing some instances when we send a invite from the B-Leg back to FS and FS passes the invite to the A-Leg that the dialog on the A-Leg has not fully completed yet causing a return of a 491 from the A-Leg side causing the call to be disconnected. wanted to see if anyone else has seen something like this while running FS and if anyone had any suggestions on a fix?

A-Leg
Invite into Freeswitch
100 Trying back from FS to A-Leg
180 Ringing from FS to A-Leg
200 OK from FS to A-Leg at 15:08:14.638799
Invite from FS to A-Leg (From B-Leg below) at 15:08:14.749515
100 Giving a try form A-Leg to FS at 15:08:14.749757
491 From A-Leg to FS at 15:08:14.780968
ACK from FS to A-Leg at 15:08:14.781102
ACK from FS to A-Leg at 15:08:14.797143
BYE from A-LEG to FS 15:11:10.791963
   481 Call Does Not Exist back to A-LEG

B-Leg
Invite from Freeswitch to B-Leg
100 Giving a try from B-Leg
180 Ringing from B-Leg
200 OK  from B-Leg at 15:08:14.635670
ACK from FS to B-Leg  at 15:08:14.637044
Invite from B-Leg to FS at 15:08:14.748623
100 Trying from FS to B-Leg at 15:08:14.748954
491 from FS to B-Leg at 15:08:14.782169
ACK from B-Leg to FS at 15:08:14.782372
BYE from FS to B-Leg at 15:08:14.790714 with Cause Code 31