Im not sure if im posting this on the correct place, but i can try.

I am looking for some kind of description, documentation that explain the end to end session over internet for skype for business.
What protocols are in use for voice, video and conferencing. 
What is the network usages for one video/voice/conferencing session.

So if there are any  documents explaining some of this, I would be really happy.

Reason why I ask is after upgrading to Skype For Business from Lync 2013 we see allot more bandwith usage.

Thank you

Please let me know if this answers your queries or not?

https://technet.microsoft.com/en-us/library/gg425841.aspx