In a country like India where telecom is regulated, and using calling cards is illegal, Voip with Gtalk, Skype, Msn and Yahoo are quite popular for pc to pc chat. But for calling a phone say in the Us or Uk or Europe these Pc to Phone calling cards come handy as per minute costs are a mere Rs 2 to 3 sometimes even Rs 1.
The popularity of pc to pc chat has dried up the mkt for calling cards and a few operators still exist. u can literally count them on ur fingertips. There is cybercafe based cos like Sify Iways, and there are others like Anyuser India or India2world.
I generally use Anyuser India that after dialpad shut shop.
Yesterday i tried out the India2world card based on the mediaringtalk network. From first hand experience, id recommend u never ever to purchase the India2world cards as they are both more expensive per call and give a truly pathetic experience. Infact all i could listen to was the opposite party speaking at chipmunk speed, and the person literally h a d t o s p e a k real S L O W for me to make sense of anything she said.