IAX2 Trunk one way Audio Issues

General Help
,
#1

Hi all
I have two Freepbx Boxes
one Box a
other Box B
both internal on network but different subsets no firewall between them.
i can call site B from phone in site A but i can only hear them for 10 sec. then no sound but they can still hear me.
if they call me from site b to site A i can only hear them for 10 sec. then no sound but they can still hear me.
there is only one Nic configured in each Server with internal IP only.

side A
L51-IAX2-Trunk

host=10.51.128.20
type=friend
qualify=yes
context=from-internal

Side B
L12-IAX2-Trunk

host=10.12.128.20
type=friend
qualify=yes
context=from-internal

Thanks
Greg

#2

Must be a routing issue at the one site.
i have setup another site and it works fine.

#3

I don’t remember the solution, but it seems to me that the problem is in the router. It could be a setting for the RTP keepalive or some other setting that keeps the path open in the router.