Resolved: One way audio for remote ext, RTP and SIP ports are FWDd

1

This is the situation

Company is XYZ and has a FreePBX with Cisco SPA514G phones.
The CEO also has a RasPBX/FreePBX at his home and Cisco SPA514G phones there.

Company XYZ Firewall
40000 (SIP) --> FreePBX
10000 - 20000 (RTP) --> FreePBX

CEO Home Firewall
40001 (SIP) --> RasPBX
10000 - 20000 (RTP) --> RasPBX

CEO Office Phone:
Ext 1 100 (Registered to Company XYZ FreepBX)
Ext 2 100 (Registered over the internet to CEO Home RasPBX:40001)

Extension 2 places a call. The call completes and is answered but the audio is one way (from the inside out). If the CEO speaks, the other party can hear, but the CEO cannot hear the other side.

After writing this out, I’m wondering if both firewalls forwarding 10k-20k could be confusing, where the RTP traffic intended for the phone at the office is being diverted to the office PBX. I’m going to change the Home RTP range to 21k-41k to see if that fixes

2

Probably far simpler. The two PBX systems are essentially distinct, so I doubt your problem is unrelated to the configuration of the systems. One-way audio is usually a problem with the RTP transiting the firewall.

Without knowing more about the logistics of the thing, I’d suggest that you might want to set up the boss’ PBX so that it uses IAX to connect to and use the office PBX as it’s outgoing connection. This way, the boss’ house “office phone” would simply be an extension from the office.

There are lots of things that need to be taken into consideration, though.

3

I split the RTP ranges so that they don’t overlap, but still one way audio.

Company XYZ is now
10000-14999 (RTP)

and CEO Home is
15000-20000 (RTP)

And updated the FreePBX ranges

Still one way audio from CEO office phone ext 2. Audio only flows outbound, but not inbound.

4

Fixed it.

The CEO Home PBX had NAT=No for the Office Extension.
Set to NAT=Yes

2 way audio works now.