A bug has been severely affecting users putting callers from the public telephone network on hold. This issue caused the caller to be disconnected unexpectedly. A workaround has been implemented which has disabled the Music on Hold feature for Windows Lync clients.
Music configured as part of a Response Group will not be affected (for example, music heard by a caller when they are waiting for an agent to answer a call).
IP phones and Mac clients are not affected by this change because they do not support the Music on Hold feature. Windows clients will not be able to enable Music on Hold until this workaround is removed on the server.
More information on the status of this issue can be found at the CITES Status Page.