Microsoft KB Archive Search

Notice: This website is an unofficial Microsoft Knowledge Base (hereinafter KB) archive and is intended to provide a reliable access to deleted content from Microsoft KB. All KB articles are owned by Microsoft Corporation. Read full disclaimer for more details.

  1. Home
  2. "SIP/2.0 503 Service Unavailable" error message when you make a PSTN call in Lync Server 2010

"SIP/2.0 503 Service Unavailable" error message when you make a PSTN call in Lync Server 2010

View products that this article applies to.

Symptoms

Consider the following scenario:  
  • A user makes a Public Switched Telephone Network (PSTN) call In a Microsoft Lync Server 2010 environment..
  • The PSTN call is routed from a Mediation server to a gateway that is disconnected from the Mediation server.
In this scenario, the Mediation server rejects the call. Additionally, the Mediation server returns the following error message:

SIP/2.0 503 Service Unavailable

Note This error message only contains an "ms-trunking-peer-state" header. However, it should also contain an "ms-trunking-peer" header. 

↑ Back to the top

Resolution

To resolve this issue, install the following cumulative update:

2502810 Description of the cumulative update for Lync Server 2010, Mediation server: April 2011

↑ Back to the top

Status

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.

↑ Back to the top

Keywords: kbqfe, kbexpertiseinter, kbsurveynew, kb

↑ Back to the top

Article Info
Article ID : 2539644
Revision : 2
Created on : 9/21/2018
Published on : 9/21/2018
Exists online : False
Views : 304