If this is happening to all phones perhaps you have "Block OffNet to OffNet Transfer " set to true. Have a look at the following doc;
Setting the Block OffNet to OffNet Transfer Service Parameter
The Cisco CallManager clusterwide service parameter Block OffNet to OffNet Transfer allows administrators to prevent users from transferring external calls to another external number. This parameter specifies values as True or False. Setting the parameter to True blocks external calls from being transferred to another external device. The default value specifies False. You modify the Block OffNet to OffNet Transfer service parameter by using the Service Parameters Configuration window.
When a user tries to transfer a call on an OffNet gateway or trunk when the service parameter Block OffNet to OffNet Transfer is set to True, a message displays on the user phone to indicate that the call cannot be transferred.
Migration from Cisco CallManager release 3.3(4) to Release 4.1
To block the transfer of external calls to external devices in release 3.3(4), the system uses service parameter Block External to External Transfer. The value of this parameter (True or False) will migrate to the new service parameter, Block OffNet to OffNet Transfer, when upgrade to release 4.1 occurs.
I'm not able to access my old voice mail messages all of a sudden. The recording says something like 'the message is currently not available'. This has never happened before in all the years I have been using this system. I have t...