CUCM not sending full audio and video codec list in SDP - no video

[PerM]

Dear Community!

I'm having a problem with not getting video calls working with CUCM version 11.5. Audio works.

System setup is:

MicroSIP -> 3rd party SIP server -> CUCM -> MicroSIP

Initial setup was no SDP sent from CUCM to callee - only in OK (INVITE). CUCM only sent "audio" and "video" in contact parameter, else no trace of video capabilities.

I suspect MicroSIP then not "daring" to set video port number and only audio get a port number different from 0 in the OK (INVITE) from MicroSIP.

Observing Wireshark, 3rd party SIP server sends 3 audio and 4 video codecs in SDP to CUCM. Both audio and video have port numbers different from 0. 

But then, this is not passed on to callee MicroSIP.

CUCM has port 0 for video in ACK, so no video. This must be due to MicroSIP prior to this has answered with OK (INVITE) where SDP has port 0 for video.

Same issue when both MicroSIP clients are registred on CUCM (internal in CUCM):

MicroSIP -> CUCM -> MicroSIP

I then configured CUCM to send SDP in initial INVITE, to make sure callee MicroSIP gets the video capabilities. 

The only way to enable SDP in initial INVITE was to set Media Termination Point Required for the phone.

But CUCM then only send one audio codec to callee.

How can I make sure CUCM passes on video capabilities to the callee MicroSIP?

Settings (some listed which I think is relevant):

System/Device Pool: "default"

Location: "Hub_none"

System/Region Information/Region: Regin "default"

Maximum Session Bit Rate for Video Calls: 2000 kbps 

System/Location Info/Location: "Hub_none"

Links - Bandwidth Between Hub_None and Adjacent Locations: Not possible to add, "already configured"

Intra-location - Bandwidth for Devices Within This Location: Video Bandwidth Unlimited.

Location RSVP Settings: No Reservation.

Device/Trunk: "3rd party"

Device Pool: "Default"

Location: "Hub_none"

Media Termination Point Required: True

Retry Video Call as Audio: True

SIP Profile: "MySIP"

Device/Device Settings/SIP Profile: "MySIP"

SDP Information:

SDP Session-level Bandwidth Modifier for Early Offer and Re-invites: TIAS and AS

Trunk Specific Configuration:

Early Offer support for voice and video calls: Mandatory (insert MTP if needed)

Device/Phone:

Device Information:

Common Phone Profile: Standard common phone profile

Product Specific Configuration Layout:

Video Calling: Enabled

Location: "Hub_none"

Protocol Specific Information:

MTP Preferred Originating Codec: 711ulaw (same only codec sent in SDP to callee. Can change to 711alaw, which is then the only one in SDP)

Media Termination Point Required: True (else no SDP in initial INVITE from CUCM).

SIP Profile: "MySIP" 

[Jonathan Schulenberg]

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.

[PerM]

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:

Device/Device Settings/SIP Profile: "MySIP"

Trunk Specific Configuration:

Early Offer support for voice and video calls: Best effort.

Also changed in Trunk and Device:

Media Termination Point Required: False

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

[Maren Mahoney]

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

[Jonathan Schulenberg]

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.

[Maren Mahoney]

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

[PerM]

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:

• Early Offer support for voice and video calls: Mandatory (insert MTP is needed)
• MTP still not used (deselected).
• SDP Transparency Profile: "Pass all unknown SDP attributes"

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:

• INVITE from caller MicroSIP via 3rd Party SIP Server into CUCM includes SDP with audio/video/non-zero ports/bandwidth
• INVITE is passed on to callee MicroSIP without SDP
• Calle MicroSIP answers with ACK inducing SDP where audio codec list has non-zero port/bandwidth but video has port 0/no bandwidth. I suspect this is a default behavior, maybe even according to standards. MicroSIP does not suggest video if caller has not stated it supports it. I do agree that early offering of media should not be needed, this can be negotiated later in the ACKs. But if then skipping video is a default, I will not make video work with CUCM and MicroSIP.

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.

• Initiating an audio call (no video) also result in SDP being removed by CUCM
• Calling from an Innovaphone via 3rd Party SIP server and CUCM to MicroSIP also gets the SDP removed by CUCM

I struggle with locating any logs in CUCM which might show some errors.

[Roger Kallberg]

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.

[PerM]

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:

• MicroSIP@CUCM -> CUCM -> 3rd party SIP server -> MicroSIP
  • Early Offer (SDP in initial INVITE), video is working

But these do not work (no Early Offering, no video):

• MicroSIP@3rdPartySipServer -> 3rd party SIP server -> CUCM -> MicroSIP@CUCM
• MicroSIP@CUCM -> CUCM -> MicroSIP@CUCM (i.e. CUCM internal call)

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?

[Maren Mahoney]

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

[PerM]

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

[Maren Mahoney]

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

[PerM]

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

[PerM]

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.

[Carlo Poggiarelli]

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