If your 21--old enough to drink, get drunk, and have sex--then YOUR old enough to be mature about this.
1. Taking your phone off the hook is NOT mature..
2. Mistakes as well as dicisions we make--truly shape the person we are. Sounds to me like your pretty shallow right now. I say that becasue if you were mature enough to drink with this person, and OOPS have sex, then you should be mature enough to NOT use alachol as an excuse for your mistake. It's quite pathetic.
Solution: Put you phone back on the hook, when he calls do not discuss this on the phone. You didn't have sex on the phone did you (I dont think so--therefore, its possible to meet with him face to face). And, grow up!
Explain that your not truly sexually attracted to him, you do not see a long lasting romantic future betwwen the both of you; however, you do cherish the fact he TRUSTED you with the loss of his virginity.
Until this person meets another and moves on--I might say it IS your responsibility to somewhat coddle his feelings right now and be his friend. You see, when you woke that next moring you were "already over It" but thing is, "he was not", and becasue of this you need to be more understanding and mature. Possibly by taking time (in person) with him as his friend you may discover nothing new--but I think the result will be healing to his emotional well being. With this both of you can move in the directions desired.
Until then, stop being so cold hearted and thinking only about you!