I'm trying to make an audio+video call between a VSX 8000 and a Grandstream GVC3200.
The GVC3200 unit supports H323+H239 and SIP+BFCP.
The VSX 8000 unit is running firmware version 184.108.40.206.
I tried to use SIP to make a call, but it failed to establish. Does the VSX 8000 w/ 220.127.116.11 support SIP with video?
I then tried to make an H323 call, and it actually established. However, there was no audio or video flow (no RTP). There are no network/firewall issues.
I guess they're having trouble negotiating the codecs, or maybe even don't speak the same protocol.
I dumped a packet trace between them, but I'm not an H323 expert. I don't know how to determine what they disagree on. Would it be of any help if I posted the trace here?
Please note that I've successfully called from a GVC3200 to another brand/model, such as Cisco SX20 with both H323 and SIP. I also successfully called the same Cisco SX20 from the VSX 8000 with H323... So I don't see why I can't do the same with VSX 8000 and Grandstream GVC3200.
Thanks in advance,
welcome to the Polycom Community.
The community's Video FAQ contains this post here:
The above FAQ post shows a Call Setup in H.323
Please ensure to provide some feedback if this reply has helped you so other users can profit from your experience.
Polycom Global Services
I went through the FAQ (very useful, thanks), and my trace seems to suggest that everything is going as expected until right after the last step in the FAQ.
How many openLogicalChannel and openLogicalChannelAck pairs am I supposed to see in a correct transaction?
I'm seeing several. These are the openLogicalChannel packets I see in sequence::
g711A, h224, g722-64k, genericVideoCapability, h224 (again)
These are the tsapIdentifier values for each one of these:
6005(endpoint1), 6011(endpoint1), 3231(endpoint2), 3233(endpoint2), 3235(endpoint2)
I also see 5 openLogicalChannelAck with the following tsapIdentifier pair values, in sequence:
Does this sound ok?
After the last openLogicalChannelAck packet, I don't see anything outright strange (I'm not an H323 expert though), except for this (repeated several times):
Payload type=RTP Event, Unknown (126)
Further down, I see lots and lots of messages such as:
PT=ITU-T G.711 PCMA
There's nothing else really, until the call is manually terminated.
During the call, only audio seems to work. No video.
How can I debug this further?
I think the VSX 8000 supports H.264 video. However, when it negotiates with the Grandstream GVC3200, it does not offer H.264, but H.263 and H.261 instead. That's according to what I could read in the terminalCapabilitySet exchanges.
Why is that?
How can I force Polycom to advertize H.264?
The Grandstream device offers the following:
standard: 0.0.8.241.0.0.1 (h264 generic-capabilities) - ITU-T Rec. H.241 H.264 Video Capabilities
By the way, what should I look for in the traffic trace to find out which video codec was actually selected after the endpoints advertised their capabilities?
I'd like to know if H.264 or H.263 was finally agreed upon, etc..