Being able to call every day is one thing having the time to call is another, to help the new recruits to settle in and to take their minds of home (homesickness) they are kept very busy for the fist 10 weeks of basic, he will call home to tell you he is short of cash, phone is broke, phone out of credit? (not from calling home), if things are getting a bit tough (finding out there are two 5 O'clock in a day) he will call home to vent then get on again.
It's not he is not grateful for all his mother has done, he is, and one day may remember to thank her. but he will be on a new journey and will get back to you when he can, think of it has a Butlins holiday camp with more fun???