Jio4G voice works on the concept of providing clear voice call on VOLTE.the quality of call is good to very good during night but average during daytime.since they are provinding the services free of cost, to my surprise the negative factors of jio is very less.they provinding much better service than some other costly networks.the layout and design of this app is good you can directly use it as and sms app as well as managing your jio sim.you have to keep it online for calling and using other services.overall it is a great app.