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Lync 2010 NAT and PSTN-IP cause 1-Way Speech path RRS feed

  • Question

  • Hello All,

    We have a Lync 2010 with Single NIC and Single IP address (Internal).  We have an Edge Server working fin with a defined NAT IP.  BUT for our FE Server and Co-resident Mediation Server the Defined PSTN IP is not being placed within the SIP header to our SIP Trunk Carrier.

    We do not have any SBC or SIP/TDM Gateway.

    Calls Inbound or Outbound connect with SIP 5060, Send 200,183, etc... messages and connects.

    Lync can send RTP to Carrier - No Issues.

    Carrier attempts to send to Lync but the SIP INVITE 200 message defined the Internal IP not the PSTN IP.

    Questions:

    Does the FQDN Need to have a PUBLIC DNS record?   From+18005551234@LYNC.Company.com_

    Here is the Get-CsNetwork for PSTN gateway and FE Pool below. 

    Identity : Carrier/Pstn/1
    ComputerFqdn : Carrier
    IPAddress : 0.0.0.0
    Interface : Pstn
    InterfaceNumber : 1
    ConfiguredFqdn :
    ConfiguredIPAddress :

    Identity            : lync.company.com/Pstn/1
    ComputerFqdn        : lync.company.com
    IPAddress           : <Public>
    Interface           : Pstn
    InterfaceNumber     : 1
    ConfiguredFqdn      :
    ConfiguredIPAddress :
    Identity            : lync.company.com/Pstn/1
    ComputerFqdn        : lync.company.com
    IPAddress           : <Internal>
    Interface           : Primary
    InterfaceNumber     : 1
    ConfiguredFqdn      :
    ConfiguredIPAddress :
    Identity            : lync.company.com/Pstn/1
    ComputerFqdn        : lync.company.com
    IPAddress           : <Internal>
    Interface           : External
    InterfaceNumber     : 1
    ConfiguredFqdn      :
    ConfiguredIPAddress :

    Monday, May 20, 2013 6:55 PM

Answers

  • Correct. Mediation does not support a NAT IP field like Edge server. Unfortunately, you will not get this to work without a SIP ALG or SBC in between Lync and your SIP carrier. 
    • Proposed as answer by Lisa.zheng Wednesday, May 22, 2013 11:54 AM
    • Marked as answer by Lisa.zheng Sunday, May 26, 2013 12:16 PM
    Tuesday, May 21, 2013 1:41 AM

All replies

  • This configuration requires a NAT firewall with SIP Application Layer Gateway (ALG) capabilities to do the SDP translation. Lync Mediation does not have the capability to define a different media IP. My recommendation would be to invest in an SBC to handle SIP translation between Lync and your SIP carrier.
    Monday, May 20, 2013 8:02 PM
  • So Lync 2010 Mediation server does not support a PSTN IP or NAT IP field similar to the Edge Server Configuration?  What if i Define an Interface with the PSTN IP, or add the IP to the Primary Interface?

    Need something other then SIP ALG or SBC for a solution (no budget nor access)

    I appreciate those options but were only using this for 10/20 people.

    Monday, May 20, 2013 11:08 PM
  • Correct. Mediation does not support a NAT IP field like Edge server. Unfortunately, you will not get this to work without a SIP ALG or SBC in between Lync and your SIP carrier. 
    • Proposed as answer by Lisa.zheng Wednesday, May 22, 2013 11:54 AM
    • Marked as answer by Lisa.zheng Sunday, May 26, 2013 12:16 PM
    Tuesday, May 21, 2013 1:41 AM