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A staff member has a Direct In Dial (DID) number of 03 8320 8111 , their extension no. is 111 and their voicemail box is also 111. i.e. the last three digits of their DID.
In this case you would set the Extension Length to three (3) indicating that the last 3 digits of the DID are to be used as the voicemail box.
So 03 8320 8111 becomes VoiceMail box 111.
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