It’s too much trouble for you and DH to have to be managing that for BM. I would start putting limits on that. Maybe once a week. And if you’re busy you aren’t answering.

I think that touching base for a short amount of time each day is ok as long as there is no behavior change in the skid after the call.  

If the skid does a 180 after the call, then parent is probably saying things to make skid miserable at that house and if that happens, then phone calls need to either be stopped or put on speaker phone or held in the same room.  Parents that PAS a skid will want the skid to hide so they won't be caught.  

The child is in Kindergarten maybe 1st grade. What makes you think their telephone call is about parenting? Is ncp saying "be good for blank" and "remember to brush your teeth". OR is ncp say ---gosh I hope your ok there, do they feed you enough?. Are you scared being at CP house...? Did you sleep ok? Did CP give you your own room yet/?? Dont worry you can come home soon. DONT worry about anything...

Tell me about the parent child relationship before the mom and dad broke up. Did ncp just fly in all of a sudden on a broom stick last month? OR were dad and mom together under the the same roof since the child was born?

Add: why does ncp only see the child for less than equal than cp? What ncp criminally charged with abuse, negelct? IS ncp a drug addict?

I was in the same situation with my wife. Her ex would call nightly, even when it was bordering on past the skids' bedtimes and even while we were on vacation.  When we first got together I thought "how great that this guy cares about his kids enough to call them every night". However after getting to know the guy, and his lack of being a parent in general, and other issues he has (bad mouthing me passively to my wife, showing up late regularly to get his kids, only seeing his kids once a week for a few hours, etc)  it became obvious his phone calls were more about maintaining control and causing problems rather than actually giving a general crap about his kids. Don't be fooled. The ex does this to maintain control, including in your house and family. Do not allow it. Your spouse needs to set boundaries. We tell the skids they are welcome to call their father anytime they want, whenever they want and encourage them to do so. Guess what? They rarely do! (Just goes to show you what kind of relationship he has with them) He also has designated times when he can call that is on certain days (not every night!) only at a certain window of time. If he does not call during those times the phone does not get answered. End of story.