If some of the calls were all to his gf, maybe he was just calling to see if she was home. Once she answered, he left the party. May have gotten food for her too, as the cabbie said they got alot of food. Call to her when he got back to the dorm was to say, "I'm here, come on over!" (I recall reading that he made a call before he went into the dorm; I commented that this made perfect sense since cell phone reception is almost non-existent in Edens.)
Strike that "all" after "calls were" :/
I think his g/f is out of state. Texting or getting her answering machine.
That makes sense.