look at it like this, he owes you a phone call at the very least, If he had your number on his work phone he should be able to get it back fairly easily to get the number off it.
If he was changing his phone he would have let you know, he didnt, so why do you think he didnt let you know?
so to sum up, what do you really know about this guy, facts, address, age, home phone number...?
Like I have said if he wants to get in contact he will, he chose not to call you again, he choses not to make himself available to you.