If TM was standing at the payphone waiting for his call, from HE cell phone, two things wouldn't add up. First, she'd have been caught on that same video waiting. Secondly, she would have actually ANSWERED rather than all of those missed calls.
What if, in a panic, SM had the phone belonging to HE, and just redialed the last number she had dialed, thinking it would connect him with TM (who had the phone of SM)?
What if HE had saved the pay phone number in her phone under his contact name, thinking it was a new number for SM?
not sure if i am making sense, but trying to go along with this line of thought.