The real issue here is that DH isn't allowed to actually parent his son, for some reason. The correct answer here should be him telling SS that he loses his phone until he's prepared to call his mother back - because it's rude for SS to not return phone calls, even to someone that DH hates.

But instead, it will be DH happy that SS doesn't want to speak to BM, and also not wanting to push him because he's afraid of his own kid.

So, really the right answer for you is, indeed - "disengage".

If your husband wants to try to work with BM and his son (if this is possible) he could come up with a compromise such that calls will be responded to within 24 hours by SS either by return call or a text...that way missed evening calls are not such an issue and SS can text back if he doesn't feel like talking. 

But as others have said above this is not your problem. Let your husband deal with it. 

It SS has his own phone,  How is BM going to blame you.  You should let BM and SS work it out themselves.  Like normal family's do.  It's up to her to not let SS control everything 

Honestly I would go back to court and have that clause removed. Till then the only thing I can think is to remove the phone until he makes the call. You can explain to the court that he has his own phone and you aren't preventing the kid from calling but he and BM are playing games.

My dh's ex would call several times during SS's visit. It was very annoying. The ex had custody and could not allow ss to visit his dad without interruptions. What the ex was really doing is spying on our household. SS would answer the phone and immediately head for another room, but on his way you could hear his part of the conversation and it was obvious that bm was giving ss the 3rd degree on what was going on at our home. 

In my personal opinion, I think the kids should be able to visit their parent withoug ANY interuptions from the ex. Just my opinion.

DH needs to invoke a phone review schedule with SS.  Once a day, at the same time, DH and SS sit down and check for missed calls from BM.  If there are any, SS immediately replies by text with "Yes, mom?  I saw I missed your call."  

End of problem.  Replying ticks the box on complying with the divorce decress 24 hour reply stipulation.  If SS does not engage with BM beyond that. So be it and it is BM's issue to deal with with SS.

Lather..... rinse...... repeat.

Ring Ring---HI it's mom and it is MY call time,  call me back

a few minutes later, Ring Ring--It's mom, call me back ITS MY call time

A few minutes later, RING RING-Its mom and its my call time call me BACKK

a few minutes later, RING RING--listen BUDDY,,uuuhhh,,mmmmmm, you better let the kids call me you know it my call time.

a few minutes later, ring ring- HI its Grandma- uhhh call me

A few minutes after that ring ring- Hi, its your neighor Mrs. Blah blah  your neighbor from YOUR home, call us., (wtf is she calling our house for i thought)  

A few minutes after that ring ring- HI its The pastors wife, uhhh, we hope you are doing ok , call us. we are praying for youuuuuuuuuuuuuuuu

---------

What your going thru is nothing new. Our situation was a little different, we could not be busy playing outside without bm blowing UP our house phone up to 12 times a day when you add all the bs calls from people we didnt know. lol Pre-cell phone junk. Thank GOD

. Your ss has a phone. Dad should sit down with him right in front of him and MAKE HIM call his mom.

Better yet, moving forward---BM kiddo will call you at 12noon OK? I will see to it.

JMO