Sorry to hear you're having to interoperate with Teams. It's a unique form of 
sadism I wouldn't wish upon anyone.

A few theories:

1) Microsoft doesn't like the "bare" Contact header-value here:

   Contact: sip:+MY_FROM_PHONE_NUMBER_HERE@MY_FQDN_WAS_HERE:5061;transport=tls

Unlike the careted one right above:

   P-Asserted-Identity: <sip:+MY_FROM_PHONE_NUMBER_HERE@MY_FQDN_WAS_HERE>

A bare URI absent other header-params is of course completely legal, but I'm 
really trying to get inside the imaginary world of antisocial "Microsoft SIP" 
here. 

2) Could it be that antisocial "Microsoft SIP" sends 400 as a way of objecting 
to something in the SDP, e.g. where a non-demented SIP stack would send "488 
Not Acceptable Here" or "415 Unsupported Media Type"?

I know you've said you tried multiple clients to rule that out, but I wonder if 
the thing it's objecting to hasn't been ruled out that way.

3) I saw this media line in the SDP:

   m=application 41356 <unknown media type> 

What's that?

-- Alex

> On Dec 29, 2022, at 9:51 AM, Brandon Armstead <bran...@cryy.com> wrote:
> 
> Outbound calls from my SBC into Teams (Polycom -> SBC -> Teams) always result 
> in a 400 BAD REQUEST.
> Example invite below:
> https://pastebin.com/F1G1Ce59
> I've taken care to make sure numbers are all E.164 format in From/To/Contact. 
> I've also taken care to make sure that FQDN is used in Contact and 
> Record-Route header.
> I've tried many different variations and have followed the SIP information 
> here:
> https://learn.microsoft.com/en-us/microsoftteams/direct-routing-protocols-sip
> I've also tried several different clients (Bria, Polycom CCX 600, 
> Grandstream, etc) to see if maybe it was something in the SDP or otherwise 
> causing an issue.
> SIP Transport is TLS, RTP is SRTP
> I might also add that OPTION pings are active and Direct Routing Endpoint is 
> active, so this is successful. I also am able to receive calls FROM teams to 
> my IP phone(s) without issue. It is only when I try and call INTO teams 
> (INVITE -> Microsoft Teams) that I always receive a 400 BAD REQUEST to my 
> INVITE.
> Any help is appreciated, thank you!
> 
> - Brandon
> 
> __________________________________________________________
> Kamailio - Users Mailing List - Non Commercial Discussions
> To unsubscribe send an email to sr-users-le...@lists.kamailio.org
> Important: keep the mailing list in the recipients, do not reply only to the 
> sender!
> Edit mailing list options or unsubscribe:

-- 
Alex Balashov | Principal | Evariste Systems LLC

Tel: +1-706-510-6800 / +1-800-250-5920 (toll-free)
Web: http://www.evaristesys.com/, http://www.csrpswitch.com/

__________________________________________________________
Kamailio - Users Mailing List - Non Commercial Discussions
To unsubscribe send an email to sr-users-le...@lists.kamailio.org
Important: keep the mailing list in the recipients, do not reply only to the 
sender!
Edit mailing list options or unsubscribe:

Reply via email to