Within a certain radius, jamming or rehearsing using Sessionwire may be possible - however this is not what Sessionwire was designed for.
Due to the laws of physics, jamming in real time with anyone over the internet outside of a certain radius is and always will be next to impossible - barring a major breakthrough in quantum teleportation and entanglement.
Sessionwire's transmission of audio and video at high quality results in some latency that most performers would find distracting if attempting to jam or rehearse in real time. This is unavoidable and Sessionwire promotes workflows that accommodate this latency.
Maintaining the integrity of the audio at a high bitrate is the number one priority with Sessionwire.
For a longer, more in depth article about why jamming or rehearsing over the internet will remain unfeasible for the majority of musicians, here's an article written by Sessionwire founder and CTO Robin Leboe.