In Season 1, Scott's cell phone is a Blackberry Torch. ((Screencap 1x06 3:45)) His first one lasts until 1x06 - Heart Monitor, when Derek smashes it in the parking lot to prove a point. It's replaced with the same model.
In 1x10 - Co-Captain, Derek steals Scott's phone before sacrificing himself to the Argents, so that the phone can act as a tracking beacon. Stiles figures out that this is where the phone must have gone.