I have personally used Telenor services and I would say if you live in a locality where you get the signals of Telenor and you are among those people who have to make a lot of calls then it is the best choice available in the market.
As an example, by making just a recharge of Rs 8, you will get local call rates of 25p/min and that too for a period of 90days. So call rates are much cheaper when you campare with market leaders like airtel, voda or reliance.
However, on the downside, the problem with Telenor is that its towers are very few and only located in urban areas so when you will be going to rural areas, you won’t be able to make any call. The customer care service is also not as good as that of airtel or vodafone.
My final verdict is that if you want to enjoy cheaper call rates and have a back up sim of some other company which you can use in remote areas, you should try Telenor service.