Consider the following scenario:
The Lync dial-in conferencing feature is deployed in a Microsoft Lync Server 2010 environment.
The hotfixes for Lync Server 2010 that were released in March 2012 are installed.
You create a dial-in conference.
Several users dial the access number and then input the conference ID to connect to the conference. The users call into the conference by using PSTN telephones.
In this scenario, certain users receive the following error message and are then disconnected from the call:
Sorry I can't seem to connect you to your meeting right now. Try your call again later. Goodbye.
This issue occurs because a race condition causes Lync Server 2010 Front-end server to respond with an invalid variable to a request from Lync Server 2010 Conferencing Attendant. Therefore, the Lync 2010 Conferencing Attendant cannot transfer the call to the conference.
To resolve this issue, install the following cumulative updates:
2701655 Description of the cumulative update for Lync Server 2010, Unified Communications Managed API 3.0 Runtime: June 2012
2701659 Description of the cumulative update for Lync Server 2010, Conferencing Attendant: June 2012
To work around this issue, restart the Lync Server 2010 Conferencing Attendant service.
For more information about dial-in conferencing in Lync Server 2010, go to the following Microsoft website: