PBX not sending video

Hello everyone!

I’m having some issues with video calls between IAX2 trunks.

Here’s my setup.

Using Grandstream GXV3275 with SIP registration for video calling on both offices.

Office 1
Vmware VM Elastix 2.0 with Freepbx 2.7 and Asterisk

Office 2
Appliance Elastix 2.2 with Freepbx 2.8.1 and Asterisk

There’s a IAX2 trunk between the two offices.

Case 1 - When office 1 calls office 2, office 1 sees video, but office 2 don’t.
Case 2 - When office 2 calls office 1, there’s no video in either office.

I made a tcpdump for Case 1 and all I can see is that office 1 receives video but don’t send.

All traffic is allowed between both offices in their respective firewalls.

What info do you need to help troubleshoot this?.

Thank you very much.

Out of interest did you find a solution? I have a similar issue using Cisco CP9xxx phone with Camera and iOS app. Video calls work when both units are on same PBX but not if on different ones.


Are the “different” ones in different locations/networks?

If so, you could be seeing a codec support problem with the ITSP. You might also be seeing a Codec preference problem: G711 (for example) gets selected because it’s preferred even though the call is requesting a VIdeo codec.

Thanks. Yes sort of, 2 different PBX but both on the same network as it happens. While I did try to prioritize Codec, I do have audio ones first followed by video, would I be better off making the video highest priority?

More importantly, I take it from your reply that there is no reason why I should not be able to make video calls between 2 PBX via IAX2 with a Cisco handset?

On no - there are a ton of reasons why this wouldn’t work. Most of them are stupid things that the system does just to spite you, but eventually you should be able to get it working.

As a matter of course, I’d set the Video Codecs highest in the codec order - part of the connection process is to walk down the list of requested codecs, in order, and settle on the first one that matches. If you have audio-only codecs first, the system could reasonably decide that that’s “OK”.

Thank you, it would appear that I’m making progress and that it is a codec issue of some form. If I disallow all and only use h264 (a codec that the Cisco phone likes and works fine for inter-PBX video calls) I get the following error message;
ERROR[18506] chan_iax2.c: No best format in ‘(h264)’???
The h264 codec is selected in both SIP and IAX settings. I’ll continue my investigation however I wondered if you may be able to shed any light / make a suggestions yourself?

Many thanks.

So following a bit of trial and error, I have found that no matter what order I put the codecs in (within Truck or extension settings) the first Audio codec is always the one that’s picked. Leading me to the conculsion that I need to make some changes to the extensions_custom.conf.

However this is where I start to get a little out of my depth knowledge wise.

Could someone give me an example of the dial plan I should enter so that all calls that start with 8xxx (this being my prefix for internal calls followed by internal extension number) are forced to codec h264 and then 8xxxxxxxxxx calls are left alone (i.e. use the audio codec) for external calls placed from that server.

Many thanks.

I’ve never done this (working strictly from memory watching other threads on here), but there have been several discussions over the past year about this. Scan through the archive for H264 and see what you find.

Just to update. I’ve eventually found a solution. If the connection between the two PBX is changed from IAX2 to SIP Trucks, it works fine, video calls back and forward between both boxes.


Can you send me your SIP Trunk settings that worked to send video between 2 systems?

Hi. I don’t have those PBX anymore.
In my particular case it was a codecs problem.
Both PBX had H.263+ as codec, and, the phones had H.264, but the setting was hidden so I couldn’t find it.
Also, I had a NAT issue, phones were using NAT when they didn’t have to.
Hope it helps.

It’s been some time but my settings as I can best remember are as follows. I believe the main issue maybe that I seem to remember you need to create a unique extension on both PBX for authentication. I hope it works for you.

username=unique extension number
host=IP of remote PBX
fromuser=Same unique extension number

secret=xxxx of remote unique extension user
host=IP of remote PBX

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