Put yourself in the boy friend's place.
He is far away working, and misses you. So he gives you a call.
What do you say?
You are just gushing with joy over the old friend's call, and to heck with poor BF!!
The BF waits a long time and calls back, only to learn you are still talking with the old friend.
Right about now he is feeling pushed aside, and a little jealous at all the fuss about someone you really do not even know. It would have hurt your feelings, wouldn't it?
Talk to him about it if it really does bother you.
But keep in mind the BF has feelings too!!
( Didn't mean to be too harsh here. Good luck with the old friend and the boy friend! )