long distance relationship?

my boyfriend and i have been together for almost 3 years he is a truck driver an is gone most of the time but thats never been the problem because even when he isnt here we constantly text,facetime, talk on the phone for hours but lately especially the last few trips he has made it seems he never has time for me i mean we could be talking on the phone first time out of the whole day and the minute one of his "buddies" as he says calls he automatically says i gotta take this ill call you back ... im at that point were im starting to feel like he is talking to another women, i dont want to think that or feel that but its just how i do he is constantly busy for me im a full time worker and a full time student and i manage to always find time to call him at lunch or break and text him in between and he cant do that he always replies i cant talk right now and its very upsetting to me. WHAT DO I DO?