Voice over Long-Term Evolution (VoLTE) is a standard for offering high-quality HD-voice communication wirelessly over 4G LTE network, being a new technology even 4G capable mobile devices need addtional hardware and/or software support to be VoLTE compatible. Today we will see how to flash and upgrade the latest Oxygen OS 3.5.7 ROM on OnePlus2 device to enable the VoLTE capability for Reliance Jio network in India.