Oh... I was sure it works. Anyway it's not a problem as I don't remember myself using this option ever.

In Israel I didn't test myself the VOIP on cellular providers, but as much as I know they do allow you to use those services almost with not capping on their end.
A couple of months ago there was an issue that one big carrier limited or even blocked the usage of VOIP on their network. They have even made new clients to sign this term in the contract. However, the ministry of communication made them stop this behavior.