Outbound Gateway hang up at 30 seconds with no answer

[Sean Devoy]

My users are complaining that SOME (not all) outbound calls ring 4 times, then go to busy signal.  The FS log shows connection and status "entering state [early][183]" then 21 seconds later "Originate Failed.  Cause: NO_ANSWER", then hang-up.  It should at least go to the receiving ends voice mail.

Why hang-up?
Why busy signal?

Bridge string is:
bridge(mailto:{sip_from_uri=4104440002 at 64.136.173.30,sip_from_user=4104440002,sip_from_host=64.136.173.30}sofia/gateway/voip-innovations-outbound/14432997994)

FreeSWITCH version: 1.10.2-release-14-f7bdd3845a~64bit (-release-14-f7bdd3845a 64bit)

Any ideas would be a  great help.

Regards,
Sean