think of it as a visit...she is visiting her parents....every 4/5days...thats not bad...
Sorry , I missed the every 4/5 days , then , he should not have an objection. But it is better if she talks to parents when he is around , be may be seeking some attention and would feel left out if she is on phone and he is waiting for her to come off of it.
I myself personally feel annoyed if I see anybody on the phone for long time, just chit chatting with someone else and I am waiting for them to come off the phone so that I could talk to them about something.