I had a client with a similiar issue. After approximately 5 minutes the calls would drop going across the WAN. Local calls were fine, only LD and/or International calls would drop when traversing the WAN. Pretty much the same set up as you.
What ended up being the issue for me was a missing command:
H323-Gateway voip interface
The previous engineers who installed it did not add this command, among others. The funny thing is this environment had been up and running for a couple years with no issues until one day it started failing.
Anyways - verify your H323 configuration on BOTH gateways (binding and interface commands)
One other thing to check is your firewall configurations. If you're running an ASA or PIX with an older image, there is a bug with the H323 Inspect which would cause timeouts.
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The short answer is that you don't.... That isn't entirely true while at
the same time it kind of is, but for the most part you don't configure
the softkeys. You enable or disable them via TCL. Here is the long
answer. Be sure to read the whole thing or e...
Topology: IP Phone > Switches > Microsoft NPS setup to forward 802.1x
proxy to > ISE 2.1 patch 3 Authentication: EAP-TLS using Cisco MIC SANs
Phone Models 802.1X support? 802.1x flavor Addtl Comment EAP-MD5 EAP-TLS
Cisco 3905 Y Y N Cisco 6911 Y Y N Cisco ...