The 12-button grey phone was found next to the former president’s after Thomas Crooks opened fire and was shot by the Secret Service.
It is thought to have something to do with the “rudimentary” explosive device that was discovered in his car, according to the FBI.
Authorities believe that rather than causing a large explosion, the intention was presumably to cause distraction or harm to law enforcement.
Crooks, 20, gave Mr. Trump a minor graze on the ear during his speech to supporters on Saturday in a field in Butler, Pennsylvania.
Investigators are looking into his background to determine why.
The gunman managed to secure a perfect location on a roof some 130 meters away, and it seems that those who saw him warned others, but they were either ignored or not taken seriously enough.
Crooks had purchased fifty rounds of ammunition from a nearby gun store before driving to the location and parking at a gas station roughly three quarters of a mile away.
