For all 4G phones without VOLTE capability they have to use Jio4GVoice app to make/receive calls/SMS from this Jio number. The sad part of this app is that this app is online only if you are connected to the Jio 4G data connection else it goes in the offline mode. Which means that the moment you connect to your office/home wifi this app goes in the offline mode and hence you cannot make/receive calls/SMS on the number on which you have activated the JIO connection. Practically the JIO connection makes sense only if you have a VOLTE phone. Without VOLTE phone you will