We have a line that takes calls for drug perscription orders over the phone via a message system. the customer leaves personal information in the message, we recieve the message the next day and order their perscription. The problem is if they pause for more than 5 seconds during that message, the system automaticly hangs up on them. How can i lengthen the amount of dead time that voice mail allows before it terminates a phone call? I would like to extend it to like...15 seconds.