Routing Asterisk traffic evading a VPN

pgb asked:

I have two offices set in two distant locations, connected through a IPSec VPN (using pfSense). On one office, I have an Asterisk PBX where all the extensions connect, and the Asterisk PBX is configured with a Flowroute trunk.

Here’s some ascii diagram:

--------------          ---------------             -------------
| office 1   |  IPSec   |  office 2   |    lan      | Asterisk  |
|  pfsense   | -------- |   pfsense   |-------------|           |
--------------          ---------------             -------------
      |                        |
      |                        |
internet link 1           internet link 2

When I make calls from office 2 through Flowroute, they work perfectly fine. However, when I make calls from office 1, there’s some echo. I’m using IP phones, so the echo is not caused by analog terminals.

My guess is that the SIP traffic from office 1 is going through the VPN and then routed to Flowroute (through internet link 2).

How can I make it so the traffic is routed through internet link 1 instead? I only want to use SIP traffice over IPSec for internal calls (extensions on office 1 calling extensions on office 2, where some echo is acceptable).

My answer:

Put another Asterisk server in Office 1.

Have the two servers talk to each other (e.g. IAX) for inter-office calls, and have each of them route PSTN calls directly to your upstream provider. The provider should be able to give you sub-accounts for each of your servers, so that incoming calls can be routed to the correct one.

View the full question and answer on Server Fault.

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