my boyf went to Amsterdam at the end of last year and didn't take his phone for the same reason. He promised to text / call me from someone else's mobile once he got there. After days of not hearing from him, I started to get a bit upset and down that he hadn't bothered because he didn't care etc etc. Anyway when he came back he called me, I was a bit reluctant to answer because I thought if he really cared then he would have contacted me whilst in Amsterdam. I answered the phone and he explained that everyone that he went with left their phones at home because of the cost, and he didn't remember my number to call me from a payphone.
Maybe your boyfriend hasn't been able to get to a place with the internet, you know what lad's are like they would get a ribbing from their mates if they admitted that they were just going off to find an internet cafe to email their girlfriend!
I wouldn't worry, I'm sure that he will come back with a nice present for you!