The door had a deadbolt lock on it. There were 2 phillips screws that I could have unscrewed and tried to manipulate the lock.

Also, there was a ventilation grate in the bottom part of the doot that also had phillips head screws attaching it to the door frame. I could have easily squeezed thru.

A cell phone would not have helped. There is ZERO cell phone reception in that place due to its construction.