The current Cisco phone matrix shows trade in pricing that is available for some current models (pink highlights on "trade in promotion" row.) The special pricing will be applied to trade in of your 79XX phones. Please contact your vendor of choice on the Cisco equipment contract to receive pricing and make a purchase. You have six months following delivery to migrate to your new phones.
Important things to note regarding new phones - check with MN.IT Client Relations (find your Account Manager at Find Your Account Manager)