<html><body><div style="font-family: lucida console,sans-serif; font-size: 12pt; color: #000000"><div>Hello All,</div><div>Microsoft is rely on approved sbc vendors, where most sbc are use VIA and headers to route traffic. That why Contact header is important, also they use from and to.</div><div>Opensips is rely on route headers and use different way to route it.</div><div><br data-mce-bogus="1"></div><div>volga629 </div><div><br></div><hr id="zwchr" data-marker="__DIVIDER__"><div data-marker="__HEADERS__"><b>From: </b>"John Quick" <john.quick@smartvox.co.uk><br><b>To: </b>"OpenSIPS users mailling list" <users@lists.opensips.org>, james@ip-sentinel.com<br><b>Sent: </b>Monday, May 11, 2020 6:19:50 AM<br><b>Subject: </b>Re: [OpenSIPS-Users] OpenSIPS as Teams SBC<br></div><div><br></div><div data-marker="__QUOTED_TEXT__">I agree completely with Ovidiu.<br>The Microsoft documentation says to use a FQDN in the Contact header, but<br>this is wrong when the SBC is acting as a SIP Proxy.<br>The blog post on the OpenSIPS website explains that actually the<br>Record-Route header needs the FQDN.<br>The one exception to this is the handling of OPTIONS pings - for these,<br>OpenSIPS is the end point so it must use a FQDN in Contact.<br><br>If you change the Contact header in call setup then you risk breaking the<br>path for sequential requests, such as ACK.<br>If ACK does not reach its destination, the call drops at one end after about<br>20 seconds - exactly what you are seeing.<br><br>I have not yet found a good way to capture TLS encoded SIP. In theory, you<br>can use sngrep with the -k option to identify the path to the private key<br>file.<br>It would be necessary to start sngrep first, then start (or restart)<br>OpenSIPS. However, this never works for me.<br>I had more success using the siptrace module to capture the packets to a DB<br>table. Presenting it as a sequence diagram may be possible using the<br>OpenSIPS Control Panel.<br>Wireshark also has the ability to capture, decode and present TLS encrypted<br>SIP.<br>Another option might be to mirror the traffic to Homer in HEP format and<br>then use Homer to create the sequence diagram.<br><br>John Quick<br>Smartvox Limited<br><br><br>_______________________________________________<br>Users mailing list<br>Users@lists.opensips.org<br>http://lists.opensips.org/cgi-bin/mailman/listinfo/users<br></div></div></body></html>