The different beroNet SBC and Gateway models support a different amount of concurrent sessions. You can find more info on this topic here: How beroNet handles transcoding
NOTE: The first 2 Sessions are Test-Sessions that can be used for free. When you buy further sessions you will need to license these 2 test-sessions as well. E.g. If you buy a 4 session license, you have 4 total sessions, not 6.