I m using iphone 5s.this is LTE phone.so I m using jio 4GVoice .when u call from jio4GVoice.u r definitly fail to call. before u calling someone to connect the Jio4Gvoice atlest 5min.every time ur cellular data should on to call & call recive .very iritating app.some major problems of this app -battery drain, app should on in background, cellular data on every time.