I use airtel since 5 year. It's network is good. Many of city if you travel telecom operator are not provided you network properly but airtel is just awsome
Internet speed is good like 2mbs speed all most every where.
Phone quality is good.
Customer service is good. Over all is good
Now day all are rate for iupc but airtel all network truly unlimited. Started plan rs 149 which is best for only calling purpose