Directing Calls To A Particular Outgoing Trunk

Is there a way to force a particular device registered via SIP on the Asterisk box to use a particular outgoing trunk each time a call is placed from that device? I know how to force calls out particular trunks when a specific number is dialed but I don't know how to make the same thing happen for a device regardless of what number is dialed. Can this be handled in the extensions.conf file?