“Call was terminated on media connectivity failure.” error message when you make an audio call or a video call that includes a remote Office Communicator user

You use Microsoft Office Communicator 2007 R2 to make audio calls, video calls or application sharing. When these sessions include a remote Office Communicator user, you may find that the call first connects but then disconnects. Additionally, you receive the following error message:


However, the call succeeds after you sign out and then sign back in to Office Communicator 2007 R2.