The Microsoft Lync 2013 client may experience issues with one-way audio when the user applies the Hold feature during a call to or from the public switched telephone network (PSTN). The user of the Lync 2013 client will be unable to use the Resume feature to regain two-way audio functionality for the Voice over IP (VoIP) call.
Additionally, the Lync 2013 client displays the following error notification:
Call could not be put on hold
This issue may occur when the following conditions are true:
The Lync 2013 client was updated to version 15.0.4517.1504 or 15.0.4535.1510.
The Media Bypass feature for the Lync Server 2013 Enterprise Voice infrastructure is enabled.
The Lync 2013 client's user makes a call and puts a remote PSTN user on hold by using the Lync 2013 Hold feature.
To resolve this issue, install the following cumulative update:
2825630 Description of the Lync 2013 update 15.0.4551.1005: November 7, 2013