It has not been my experience that Microsoft Teams direct routing requires a Record-Route header on requests / responses you send to it (though their requests will have an RR and you must Route accordingly) Here is a sip trace showing a successful on-hold / off-hold scenario from one of my servers (not a freeswitch server). This is an on-hold triggered from the MS teams client, not sure if you are trying to do the reverse. One thing: make sure the Contact header in your INVITEs resolve to a single server, otherwise (if you have mutiple A records for the DNS name) you will find that MS Teams will gladly respond to a reINVITE to a completely different server than you sent from — this will manifest as not seeing the 200 OK to a re-INVITE you send, or not seeing the ACK when you respond 200 OK to a re-INVITE. daveh One thing to make sure of is that On Sep 20, 2020, at 12:05 PM, Stefan Kainz <s.kainz@wnt.at> wrote: Hello, we're trying to use Freeswitch as a Microsoft Teams direct routing SBC. So far everything works perfectly, except getting the call back from hold on an outbound call. The Problem is that Microsoft expects a Record-Route Header in every Request and every Response. I have been able to set/rewrite this Record-Route header with sip_h_ and sip_rh_ in most szenarios, but like i said - unhold on an outgoing call does not work. The hold is initiated with a reinvite with a=inactive in sdp, which does work. However, the unhold - also a reinvite with a=sendrecv in sdp does not work correctly. In the sip-trace i see that the OK ( in response to the INVITE for unhold ) gets retransmitted a couple of times, because the ACK from microsoft isn't received. This is due to the missing Record-Route Header in the OK Message. I have seen this behavior on inbound calls too, when i didnt set the Record-Route Header. Now my question: Is there any way to add the Record-Route Header to every Message on a sip-profile or gateway? Or if not, is it possible to handle a reinvite in dialplan so i could set the header manually? Maybe there is somebody who already has this working that could point me in the right direction. I know freeswitch isn't a SBC, but it would be nice to be able to use freeswitch as a Teams-SBC without Kamailio or something similar. Any help is very much appreciated 🙂 regards, Stefan _________________________________________________________________________ The FreeSWITCH project is sponsored by SignalWire https://signalwire.com <https://signalwire.com/> Enhance your FreeSWITCH install with disruptive priced SMS and PSTN services. Build your next product on our scalable cloud platform. Join our online community to chat in real time https://signalwire.community <https://signalwire.community/> Professional FreeSWITCH Services sales@freeswitch.com <mailto:sales@freeswitch.com> https://freeswitch.com <https://freeswitch.com/> Official FreeSWITCH Sites https://freeswitch.com/oss <https://freeswitch.com/oss> https://freeswitch.org/confluence <https://freeswitch.org/confluence> https://cluecon.com <https://cluecon.com/> FreeSWITCH-users mailing list FreeSWITCH-users@lists.freeswitch.org <mailto:FreeSWITCH-users@lists.freeswitch.org> http://lists.freeswitch.org/mailman/listinfo/freeswitch-users <http://lists.freeswitch.org/mailman/listinfo/freeswitch-users> UNSUBSCRIBE:http://lists.freeswitch.org/mailman/options/freeswitch-users <http://lists.freeswitch.org/mailman/options/freeswitch-users> https://freeswitch.com <https://freeswitch.com/>