If I have to tell the worst service provider than my vote goes to BSNL.Firstly talking about 3g internet of BSNL is such a joke, it does not give 3g speed never it is approximately good than 2g which they says 3g internet.At some places net is too slow that if we have to download whats app image than also we have to wait for 2 to 3 minutes which is too long to download a single image.Talking about calling its not up to the mark because sometimes it gets big issues like if we are calling someone than it says that the number you are calling is wrong even if it is correct.After 1 or 2 dials it gets connected.So its my humble request dont impress with its cheap prices, service given is very bad.