I am not sure if this is possible ...
I am not sure if this is possible, but what I would like is for the phone providers -- whether landline, mobile, or VoIP -- to provide us an option to automatically block all VoIP numbers that originate outside the country. For instance, if I am in the United States and a VoIP call is made whose source IP is from India, block the call.
Or, better yet, always block foreign VoIP calls except from countries a person has whitelisted or from numbers a person has whitelisted.
A possible benefit to doing this might be to force tech support people to be local, instead of outsourced to India.