That's why I suggested that Scorp finds out what the kids' routine is when they're with his wife. If Scorp knows the routine, he can find the holes and say "right, I'll call at X time". It's no use Scorp saying to his wife "I'm calling at X time" if his wife's schedule doesn't permit it (in my post, dinner or bath time). Get the info, make the decision, follow up.
I have to agree with Mach on this:
"I WILL be calling the kids at 7 every night. And if there is any attempt to block this, then I will be taking them back to my province with me, and I will allow you to speak with them every night at 7....."
Substituting the time you want for the time that works with you AND your wife. You have to be consistent with this. If you are and she blocks it, fire off the warning and act on it if it continues. If you call at random times, you won't have a leg to stand on; she's trying to organise the kids of a night time and you'll be interfering with that.
As for your MIL's involvement, when she takes the phone off the kids, that will be pretty obvious so document it, however I sense some mindreading when you suggest that your MIL is involved when the phone isn't answered at all. You're probably right but it's doing you NO good having these thoughts. You're holding yourself back by mindreading. Get the parenting plan in place and worry about your own life, not what your wife/MIL may/may not be doing.
Me: 31, W: 29 T: 4 M: 2 Kids: 3 (SS: 7, SD: 4, D: 3) Separated, still living together: Nov 2013 Separate bedrooms: Feb 2014 W working away; kids with me: Nov 2014