I know I am a little late on the phone thing but can you unplug the phone when you are at work and either lock it in your car or hide it in your house?

Here, you can unplug it from the phone jack and plug it back in when you come home...people just won't be able to reach your answering machine when you are gone.

Everything happens for a reason, maybe Dad needs to find that it isn't better out there, he needs to realize how good he had it here. Maybe he will find God and that is the most important thing when he finds Him he will know he is supposed to come home.