I am using Nokia Lumia 625 with Jio sim so can I make a voice call on Jio sim?
NoYou can use the data only and not make calls via jio sim on a windows phone.The reason is that there is no Jio4G voice like app on the windows store.Once it is launched you can call but now you can not.The voice call is supported with VoLTE device without the data and LTE devices access it via that app.The app provides a channel to access the encrypted network to make voice and video calls.
Will a JIO SIM work in a Nokia Lumia 520?
The Jio 4G Sim supports only 4G LTE band for internet connectivity. Furthermore, calling from Jio is only supported on handsets enabled with VoLTE with 850 MHz band. Therefore, a handset mobile must support 4G and VoLTE both to use both data and calling features of Jio 4G sim. Clearly Jio 4G sim will not work with your Nokia Lumia 520.Watch this video for more clarification about 4G, VoLTE and 3G bands,However, in the mentioned advertisements, Jio is advertising its JioFi device. JioFi creates a Wi-Fi hotspot and 2G and 3G mobile phones can connect it through Wi-Fi to use 4G internet. Also, you can make calls through Jio 4G Wi-Fi using Jio4GVoice(formerly known as Jio Join) app. Multiple devices can connect to Jio-Fi through Wi-Fi simultaneously.The cost of JioFi device is ₹1999 and thus is an alternative of buying a new mobile.Here's link to more details about JioFi from Jio's website:Best Portable 4G Pocket WiFi Router & Hotspot in India