Thank you for your question
My name is Clare
I shall do my best to help you but I need some further information first
Why has she suddenly done this?
What face to face time do you spend with the children?
In what pattern?
How many days has she stopped the phone calls for so far?
Has she actually removed their phones?
In the short term yes she can - simply by stopping then from doing so.
In the long time and if necessary you can apply for a Child Arrangement Order that re-instates the phone calls and ensures she cannot stop them.
The first step in that process is to attend a Mediation Information and Assessment Meeting with a family mediator.
If your ex will not mediate then you can then apply to the court for a Child arrangement Order using a Form C100 and paying the fee of £215.
Since the children enjoy the calls and they have being regular for so long there is no reason why they should not continue
Please ask if you need further details
You are welcome - I hope it will not be necessary