Assume that you configure the History-info Header Support feature on a Session Initiation Protocol (SIP) trunk in a Microsoft Lync Server 2013 environment. A client for Lync in the environment is configured to forward a call to a number that has an extension. In this situation, the Mediation server cannot forward the history-info header or the referred-by header to the Public Switched Telephone Network (PSTN) gateway in the environment.
This issue occurs because the Mediation server incorrectly parses the extension in the "tel" URI in call history headers.
To resolve this issue, install the following cumulative update:
2881699 Description of the cumulative update 5.0.8308.556 for Lync Server 2013, Mediation Server: October 2013