If he had the opportunity to call his son, why didn't he do that first?
See step 5 above.
Have someone else call your kid. Schit ain't hard, and plenty of ways to do it without telling anyone what is going on. "Hey, my phone is acting stupid. Can you call my son for me?" Text the kid and ask if he wants to go out for pizza for dinner, or take his GF out this weekend, or whatever.