i can'do any calls

Yes I’m also having the same problem for a few days now! 

Hi @Radu Zarif & @Gkminhas 

Sorry to hear this, we’d recommend trying the following;

For iPhone;

Settings > General > Transfer or Reset RDevice] > Reset > Reset Network Settings.

For most Android;

Settings > System > Reset options > Reset Wi-Fi, mobile & Bluetooth

For Samsung; 

Settings > General management > Reset > Reset mobile network settings

Resetting network settings will NOT reset any personal data (Photos, Videos, Contacts etc) only network settings.

Tom