Here is the phone call that made Dak Prescott a Dallas Cowboy, on both ends of the telephone.
Dak Prescott was selected as the 135th pick in the NFL Draft by the Dallas Cowboys. The Cowboys posted a video shortly afterwards of Jerry Jones and head coach Jason Garrett making the call to Dak. You can see that whole video here. But also, video was released later of the reaction of Dak and his family when he received the phone call. You can see that whole video here.
I saw Dak's video while scrolling through the comments of the FWtCT Facebook page, and Brent Funderburk recommended doing a split screen video of their reactions.