I have a Toshiba CTX100 with a 2 port Stratagy VM. When both ports are occupied,
the VM system locks up. Has anyone run into this? Tech support is stumped. Any help
would be greatly appreciated.

exactly what are the symptoms. describe "locking up".

The Voice Mail system shuts down, meaning that when both ports are engaged, the voice
mail reboots itself, locking up both ports as if busy so no one can access. There is power to the system. Lights are flashing as if rebooting, and both ports turn solid as if
in use.

You may be running out of disk space. Can you log into the stratagy via laptop or through the admin mailbox?