AT&T Wireless slapped outrageous 40,000% higher rate than Google Voice Nationwide

I recently switched from Verizon to AT&T wireless, bought a Moto G Android smart phone, installed Google Voice app. GV was setup to handle International calls. Worked fine for a few days.

Suddenly International calls started going via AT&T that caused havoc in my bill. Just four calls to India, and AT&T slapped me an unblievable $400+ i.e. 40,000% higher than GV. I cried but AT&T refused to help. AT&T requires me to sign up for $5/month plan if I want to use their 32c/min service but they do not require any agreement from me to their $3.49/min service, yes, 349 times GV rate. No agreement needed, no warning issued, no alert that their meter was running 349 times faster. Which part of the world charges $3.49/min in 21st century?

If this is not a ripoff, what it is? Yet, they can shamelessly claim "Customer First!!"