Of all sim cardsI used so far, i conclude, , i have experienced AIR TEL as the best sim card, i travel long distances (by CAR and TRAIN )but no problem of signals. but reliance is a problem specially in train. what is your experience with reliance ?
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I don't know other technical superiority of Air tell SIM card, but am convinced that connectivity across the whole country is better with BSNL than Airtel. In many places, inside the house Airtel connectivity is poor compared to BSNL. The same problem for reliance also. Quite likely due to longer distance from the tower with fewer towers for these companies. Likely things would improve for others (especially with declining efficiency of BSNL and poorer maintenance).