The main operators in Bangalore and in general in Karnataka - Airtel, Reliance, Tata Indicom, BSNL, Idea, Vodafone, etc. The leader is Airtel. When buying a sim card you need 2 photos 3x4 cm and a copy of the passport and visa. Some states may also require a copy of the C-Form (foreigner registration form at the hotel) or other documents. Stand sim cards within 200 rupees. SMS to Russia - 5 rupees, minute of conversation - from 15 rupees