I do not mean to upset anyone, so please do not take it as such.
I can understand why you want to control contact. All children will play one parent off against another given a chance, I think that is normal.
May I ask, do your children want to have telephone contact?
Perhaps you could compromise and arrange a certain day and time when he could telephone, say once a week or month or whatever you think is acceptable. That way you will have more control over the situation IYSWIM
I personally think that the court will look far more favourable on you if you are seen to be reasonable.
I obviously do not know your situation etc. but have you tried a Contact Centre, they may be able to help you in advising you.
I am sorry I can not be more constructive, but I think the only way the court will consider your application is if either the children do not want the contact or if it is causing them (and you, I think??) some form of emotional stress.
The purpose of the court should be to put the 'needs of the children first' this may not meet with what you would like, but if you can word it in such a way that it is detrimental to your children then they consider it.
I think as I said before you want to be seen as being reasonable, and that you are putting their needs first, hence if you can compromise to a set day and time this may help, and if he then does not stick to it, and does not phone then you can then ask the court to withdraw the telephone contact as I am sure it would be stressful to your children if they were expecting a telephone call and one did not occur.
I think what ever you put you need to word it from the point of view of how it affects your children, rather than yourself, although I do understand what you mean. Do they have any other regular contact?