SIP/2.0 400 Bad Request and 503 Unavailable RRS feed

  • Question

  • Hey everyone, 

    I'm trying to setup a local Lync 2010 system that we plan to eventually replace our existing PBX with and federate with Office 365. Anyhow, So I'm trying to get outgoing calling working. We have had some mixed success, our SIP Trunk provider has been seeing traffic before, but at somepoint this week something changed and I'm now getting the following error in Lync Logging...


    Start-Line: SIP/2.0 400 Bad Request

    From: <sip:LyncFE.internaldomain.local>;tag=80CCE787D00D0B2017E61C4F65BAC7BE

    To: <sip:lyncFE.internaldomain.local>

    Later on in the logs, the call fails with a 503 Unavilable error...

    From: "Jeff"<sip:user@sipdomain.com>;tag=7cee9a8070;epid=7fe073c346

    To: <sip:5551234567;phone-context=alchemy-bend@bw.bendbroadband.com;user=phone>;epid=B561B8D337;tag=ba9c9bf4f6


    ms-diagnostics: 10001;source="LyncFE.internaldomain.local";reason="Gateway did not respond in a timely manner (timeout)";component="MediationServer"


    Does anyone have any ideas I could try? I have rebuild the topology, cleaned up the various routes, and gone through all the settings several times.



    Jeff Paulson
    • Edited by Jeff Paulson Friday, October 7, 2011 8:16 PM changing the title.
    Friday, October 7, 2011 8:16 PM

All replies

  • Jeff,

    You are saying "trying to get outgoing calling working". Does it means incoming calls are working as expected?



    • Edited by Drago Totev Saturday, October 8, 2011 1:51 AM
    Saturday, October 8, 2011 1:51 AM
  • HI,

    Please check this,

    1. Do you able to ping to the SIP Proxy IP of the Service Provider from the Mediation Server?

    2. Run Wireshark on Mediation Server. Do you see any INVITES or OPTION requests flowing?


    Saturday, October 8, 2011 3:58 AM
  • You mediation server connects to sip trunk provider directly without gateway?

    The error means the calls route to a wrong gateway, so the it can not receive response from gateway.

    So please check the DNS record for gateway and the listening port or you use the correct IP address provided by sip trunk provider.


    Please remember to click “Mark as Answer” on the post that helps you, and to click “Unmark as Answer” if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread.
    Monday, October 10, 2011 8:19 AM
  • Hi guys, 

       Thanks for the responses...

    So first off, No incoming calls are not working either, I just figured it would be easier to get outgoing calling working first. Yes I can ping the SBC address that our provider has given us.

    Our provider is having us connect directly to a SBC that they have on premise. Is that acceptable? I know I was reading somewhere that we need a "Microsoft Certified gateway" is their SBC one of those? 

    Last week when I was testing, they could see traffic however, so that leads me to thing that something else is messed up, even if the lack of a MCG is a problem. I am using the IP address they gave me, so I don't think its a DNS issue.I

    I'll do some wiresharking and see what I can see...

    Jeff Paulson
    Monday, October 10, 2011 3:03 PM
  • Hi,

    It seems that you have a problem with your connection from the Service Provider. You meant SBC stands for Session Border Control? so it meas that your connecting the mediation server directly to the SIP Trunk provided by the Service Provider.

    I don't think this will work. Even though the Provider may seem to get traffic from you, there will be other interoperability problems such as SIP Messages incompatibility.

    Below are the set of Gateways that Certified my Microsoft for PSTN Integration. It's better if you can get one and connect your SIP Connection to that and connect to the Mediation Server. no point of wasting your time troubleshooting.



    • Proposed as answer by Thamara.Wijesinghe Monday, October 10, 2011 5:02 PM
    • Marked as answer by Sean_Xiao Thursday, October 13, 2011 1:27 AM
    • Unmarked as answer by Jeff Paulson Thursday, October 13, 2011 6:03 PM
    Monday, October 10, 2011 4:16 PM
  • Sorry. I have posted the URL of OCS. Please find the correct one below.



    Monday, October 10, 2011 5:01 PM
  • Hey Guys, 

    Sorry for the delay, after talking to my trunk provider they insist that it should work with their SBC. citing the following:



    As an alternative to using PSTN gateways, you can connect your Enterprise Voice solution to the PSTN by using SIP trunking. SIP trunking enables the following scenarios:

    • An enterprise user inside or outside the corporate firewall can make a local or long-distance call specified by an E.164-compliant number that is terminated on the PSTN as a service of the corresponding service provider.
    • Any PSTN subscriber can contact an enterprise user inside or outside the corporate firewall by dialing a Direct Inward Dialing (DID) number associated with that enterprise user.

    The use of this deployment solution requires a SIP trunking service provider.




    Session Border Controllers qualified for Lync Server 2010

    Listed below are the Session Border Controllers (SBCs) along with the necessary firmware combinations that have been independently qualified with Lync Server. It is recommended that you visit the vendor's Web site for the latest information regarding protocol, capacity, country support and documentation including a Quick Start Guide, release notes and any known issues.


    Qualified Product

    Software Version Tested

    Acme Packet

    Net-Net 3820 / 4500



    Jeff Paulson
    • Edited by Jeff Paulson Thursday, October 13, 2011 1:36 AM
    • Marked as answer by Sean_Xiao Thursday, October 13, 2011 1:38 AM
    • Unmarked as answer by Jeff Paulson Thursday, October 13, 2011 6:03 PM
    Thursday, October 13, 2011 1:35 AM
  • I noticed that the application server service isn't starting up.  Simular to this issue:


    However when I looked at my user's properties and it looks like my msRTCSIP-PrimaryUserAddress domain is correct. 

    But I do get a warning:

    WARNING: "RegistrarPool" with identity "1159643103" assigned to "sip:RtcApplication-ec738695-7cd2-42e3-9eb1-2e1cbf80da1c@incorrectsipdomain.com" has been removed from configuration store.

    Just like that other issue...Maybe something in our AD is messed up. I did originally have "incorrectsipdomain.com", so maybe I'm just not looking at the right  msRTCSIP-PrimaryUserAddress.

    Thanks everyone

    Jeff Paulson
    Thursday, October 13, 2011 1:42 AM