It may be possible with code to just always add a contact, not sure there is any reason not to, just isn’t typically necessary so it wasn’t there.

On Sep 12, 2018, at 8:17 AM, Sebastian Zenzerović <sebastian.zenzerovic@inet.hr> wrote:


Hello,

is it possible to add (configuration option/variable?) Contact header to outgoing gateway ping messages sent by Freeswitch?

Remote SIP peer is answering "403 forbidden" as there is no Contact header present in SIP OPTIONS.
Not a big deal since FS sees the peer as available/UP anyway but could be a interoperability enhancement between FS and Microsoft Direct routing service (https://aka.ms/dr/).

Here are the requirements:
• Must: When placing calls to the Direct Routing interface, the 'CONTACT' header must have the SBC FQDN in the URI hostname
• Syntax: Contact: <phone number>@<FQDN of the SBC>:<SBC Port>;<transport type>
• If the parameter is not configured correctly, OPTIONS are rejected with a '403 Forbidden' message

Freeswitch log:

   OPTIONS sip:sip-du-a-euno.pstnhub.microsoft.com;transport=tls SIP/2.0
   Via: SIP/2.0/TLS x.x.x.x;branch=z9hG4bKvjX0rU7K5QtKS
   Max-Forwards: 70
   From: <sip:sbc.xxx.xx>;tag=0aB5jm3SF07ve
   To: <sip:sbc.xxx.xx>
   Call-ID: 101b723c-3113-1237-6092-00155d000d46
   CSeq: 128016309 OPTIONS
   User-Agent: FreeSWITCH-mod_sofia/1.8.1-2-4f54cff36a~64bit
   Allow: INVITE, ACK, BYE, CANCEL, OPTIONS, MESSAGE, INFO, UPDATE, REGISTER, REFER, NOTIFY
   Supported: timer, path, replaces
   Allow-Events: talk, hold, conference, refer
   Content-Length: 0

   SIP/2.0 403 Forbidden
   FROM: <sip:sbc.xxx.xx>;tag=0aB5jm3SF07ve
   TO: <sip:sbc.xxx.xx>
   CSEQ: 128016309 OPTIONS
   CALL-ID: 101b723c-3113-1237-6092-00155d000d46
   VIA: SIP/2.0/TLS x.x.x.x;branch=z9hG4bKvjX0rU7K5QtKS
   REASON: Q.850;cause=21;text="4da4bb47-5ace-41b2-ba4b-6516fb4771c2;Record-Route and Contact headers are missing"
   CONTENT-LENGTH: 0
   ALLOW: INVITE
   ALLOW: ACK
   ALLOW: OPTIONS
   ALLOW: CANCEL
   ALLOW: BYE
   ALLOW: NOTIFY
   SERVER: Microsoft.PSTNHub.SIPProxy v.2018.9.10.4 i.EUNO.4