Very simple idea this, and probably easy to implement.
Recently I had the need to block calls to premium rate numbers.
I've just found out that international calls are also blocked as a result of this.
I have been informed that blocking calls to premium rate numbers also blocks international calls, it's either block both, or block neither.
My idea is therefore simple:
Allow members to block calls to premium rate numbers, but don't block international numbers as well.
This is particularly relevant giffgaff's new international pricing, which may attract new members who wish to call abroad.
All the best