I use airtel sim since last 5 year’s.after upgrading to 4g sim it will not give speed which is required.it net speed was so poor.also calling was poor.call drop problem are occur sometimes.calling and internet pakages are more expensive.he told that largest networks in india but many times there was poor network in such big cities also.customer services are worst.many time without any subscription from me he subscribe any package like caller tune, cricket score etc.it make fool to people’s.