You can't force that man to pay for something that you feel the kid should have. :?

Does dad pay CS? If so, maybe he thinks mom should be us in some of that money to cover the cell phone bill.
What happens if he decides to take your GF to court because she is allowing you to prevent him from speaking to his son?

Expecting dad to split the bill is petty. Blocking his number is childish.

It sounds like a control freak, greedy BM move.

Can you make your opinion heard by BF? "I know you don't want to pay for half his phone. Yet you enjoy the privilege of calling him on it. This works both ways. Now would you be interested in paying 1/3rd? BM will pay the other 1/3rd and SS can work to pay of the other 1/3rd. He could earn his share with good grades as well."

You COULD block him during school time and after 9pm until 6am in the morning. So you create a window his son can be contacted via cell phone by his father. And of course whenever he is home he can contact his son via the landline.

Are you going to ask him to pay for the landline too?

See, I consider this petty, because what difference does it make whether it's a landline or a cell line? Your family is still paying for it. Now, if he was causing overages, that would be another story.

If you guys are already paying for it, why would it be wrong for BF to call the kid on the phone? Revenge and grudges are only a recipe for shitty karma.

I agree though that BF should not call him on the cell phone. Why should he enjoy the benefit of something of which he disapproves?

Is his "disapproval" only a technicality? Does approval=1/2 responsibility to pay bills?

I can't be the only one thinking, "Grow. Up."

I can relate to your dilemma.
DH purchased phones for all 3 of the skids. He did this because BM blocked his number from her cell a couple of years ago. That's when the skids started getting their phones on their birthdays. Started out just fine, they would call, text, face time, with both parents. Then she started taking the phones from the children for various reasons, her sister was visiting from another country and needed a phone, used SS. Hers broke, took SD9's. Both of these times, DH shut the service off until the phone was returned to the child. Then the phones were confiscated for punishment. Then as they started texting me, they were punished. She always checks their phones and if there is a call or text, to or from me, they get punished. Now, when she is mad at DH, she takes the phones.
Perfect example, SS got in a fight at school, BM blames DH, calls him screaming at him. He wants to talk to SS, she hangs up. It's been a week, none of the children are answering his calls. He text and emails her asking for SS to call, she answers "not my responsibility". I check the phone bill on line, she is calling and texting them and vice versa.

So, should she be blocked? She is blocking DH? Using his own phone!

As long as some other way to call the kid.   Landline, etc. or your phone.  Does he have CO for phone access?