09-06-2023 10:57 PM
09-07-2023 04:19 AM
MTP is not your friend. The only scenario that video will pass on an MTP-terminated call leg is with codec passthrough on an IOS MTP, and even then the SDP m lines are limited (I can’t remember the limit off hand). You don’t want an MTP; that setting on the SIP Profile should be Best Effort.
Does the invite received by CUCM from the calling device include early offer? It needs to if you expect CUCM to send the called device an early offer without an SDP.
Is the MicroSIP softphone built as an Advanced 3rd-Party SIP Phone in CUCM? Basic doesn’t allow video SDP capabilities.
09-07-2023 05:37 AM
Hi Jonathan, and thank you for reaching out to me!
Yes, MTP does not seem to be useful. It did made the SDP appear in the initial INVITE to the callee, but only codec included was the one audio configured for MTP.
I've now changed to:
I can confirm using Wireshark the initial INVITE coming from caller (via 3rd party SIP server) to CUCM includes an SDP with 3 audio and 4 video codecs (with ports different from 0).
I've now set up a new SIP profile for the callee MicroSIP in CUCM to be a 3rd Party Advanced device.
Now the INVITE passed on to the callee MicroSIP client does not include SDP. Only trace of anything related to capabilities is in the contact parameter:
contact audio:video:+multiple-codecs-in-ans
Callee client still answers with port number for audio and port 0 for video, so still no video.
It should be mentioned that this setup works for video:
MicroSIP -> 3rd Party SIP server-> MicroSIP
Any suggestions are very much appreciated...
BR
PerM
09-07-2023 09:18 AM
I'm thinking that you might set the SIP Profile "Early Offer Required (Insert MTP if needed)" (and not make an MTP available via the MRGL), and also set SIP Profile for SDP Transparency Profile to "Pass all unknown SDP attributes" that should work. I've used MicroSIP in my classes and had 2-way video working, so there is a way.
Maren
09-07-2023 10:57 AM - edited 09-07-2023 10:58 AM
The other thing that's weird about this is that early offer shouldn't be required for video to negotiate. I'm not in a position to test this but I'd expect a delayed offer from CUCM to result in a 18X (delayed offer, early media) or 200 OK (delayed offer, delayed media) message from MicroSIP with it's full SDP offer - audio and video. CUCM would then respond with a PRACK (18X) or ACK (200 OK) with the best matched SDP per the Codec Preference List while also complying with the Region per-call bandwidth and Location aggregate bandwidth. It would be interesting to see a debug/log/PCAP of the SIP dialog between CUCM and the called MicroSIP device.
09-07-2023 01:55 PM
Agreed on the Early Offer. I was thinking that with a 3rd party SIP device, the ability for CUCM to get and pass along an SDP in the initial exchange would ensure that it's not filtering something. As it happens, in the class I used to teach we had set up a SIP Profile with the Early Offer for other reasons in the class and happened to use that for the MicroSIP devices, which is what made me propose it.
But you brought up another good point about the possibility of a Region setting preventing video from negotiating properly. I would venture to guess that the devices in the OPs environment are in the same region or they'd have mentioned it.
Maren
09-08-2023 01:11 AM
Hi Jonathan and Maren,
My setup is in a lab where I have Wireshark "all over", purpose is to explore video usage with 3rd party SIP server with/without CUCM.
All MicroSIP clients have the same settings.
If I omit CUCM: MicroSIP -> 3rd Party SIP server-> MicroSIP
I see INVITE with SDP with the full proposed audio and video coded list from MicroSIP caller into MicroSIP callee. Both audio and video have media port different from 0 and also bandwidth included - video call works well.
With the problematic setup including CUCM: MicroSIP -> 3rd party SIP server -> CUCM -> MicroSIP
The configuration is as listed previously. I have now also modified the following:
Device/Device Settings/SIP Profile: "MySIP"
Trunk Specific Configuration:
Region: Video BW set to 2000 kbps (as previously).
Location: Difficult to figure out what to set. Altered Location RSVP settings to System Default or Optional (video desired), but no improvement. Mandatory did not work at all (no call setup).
Observing Wireshark:
Why do CUCM strip away the initial SDP (Early Offer)? It could at least send audio codecs only if video was not supported for some (configured) reason.
I struggle with locating any logs in CUCM which might show some errors.
09-08-2023 08:53 AM
It would be the CallManager logs (SDL) that you should look at. Possibly you need to look at what trace settings you have for the CallManager service.
09-08-2023 04:21 AM
Hi - update on the issue:
I just now found out that video (and Early Offer) works if I call in the opposite direction - and only outbound from CUCM, i.e. from the MicroSIP client connected to CUCM. So this scenario work:
But these do not work (no Early Offering, no video):
So it might seem to work, i.e. settings worked on do as they are supposed to - but then only in one direction.
Probably something obvious to CUCM experts I need to add?
09-08-2023 05:07 AM
Having the Early Offer Mandatory on the trunk, having received Early Offer from the CUCM-connected MicroSIP client is why it works in that direction.
Do you have Early Offer Mandatory on the SIP Profile that is associated with the MicroSIP 3rd Party SIP Device as built in CUCM? If not, then CUCM would default to not using Early Offer when sending an INVITE to it.
Another possibility would be a setting on the MicroSIP client that set it to include video in the SDP when replying to an INVITE. I don't know for sure that setting exists, but if *not* sending video in an SDP is the MicroSIP default I suspect (because MicroSIP is an awesome product) that there is a way to change the setting from the default.
Maren
09-08-2023 07:11 AM
Hi,
The SIP profile used for the MicroSIP "3rd Party SIP Device Advanced" is the same as for the SIP Trunk, where Early Offer is Mandatory.
The external MicroSIP sends audio and video as Early Offer in to CUCM, but CUCM strips it away in that direction. I have not found a way in MicroSIP@CUCM to make sure video is included in Late Offer (and that might even be OK according to standards). But it should not be needed: The external MicroSIP do send it as Early Offer, and that should be let trough to the MicroSIP@CUCM.
PerM
09-08-2023 07:55 AM
Huh. Why in the world would CUCM not use Early Offer towards the locally-registered client if the SIP Profile for that locally registered client requires Early Offer?
Regardless, I agree that it should not be needed. But then why is MicroSIP responding differently to delayed-offer with CUCM than it does with your other PBX? Would you be willing to post the message exchange for us to take a look at? The "good" exchange between MicroSIP and the other PBX and the "bad" exchange between MicroSIP and CUCM?
Maren
09-11-2023 12:53 AM
Hi,
Seems like this issue is similar to the one below - which did not have a solution listed.
Need to Send Early Offer to SIP Phone from CUCM - Cisco Community
PerM
09-11-2023 03:54 AM
And probably the details are found here: https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cucm/srnd/collab11/collab11/trunks.html
But as far as I am able to understand, the setup is according to the recommendations.
09-11-2023 05:24 AM
Hi,
Can you please post a sip trace from either MicroSIP (wireshark) or CUCM so we can give a look?
Please also post a screenshot of your custom sip profile so I can replicate it in a lab
Thanks
Regards
Carlo
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