fathers day.. what is the right call

Hi,
Right sorry if a little long, but would like to know from others in sort of the same place..
I have two kids under 3.5 this will be there first fathers day.. they are making stuff at school which is fine im going to put it aside for him.
My big question is should i get the kids to call him.
Mind you all he hasnt talked to his kids for 5 months says he is going to but has not happened. he was the one that walked away and told me it was over on a phone call.. when the kids and i moved i tried for him to have a relationship with the kids. Sent texts tried to call about what he would like to do, about kids..
Im unsure if i should get the kids to call him for fathers day..
I dont want them to as, i thought as a father you would do anything for them and to not call or try and see them or even help buy them things, i dont think he should receive a call from them..if he wants to call them im happy for that.. so what do u all think.. thanks heaps hope it makes sense...