The telehealth platforms I see are terminating through the health provider itself. It does the call setup, conference setup if needed, waiting room for prior call to end, if you send a photo it can be saved to your record etc.

If this is e2e to the physicians home, how does the telehealth system do all these add in functions?

At least in the US, the requirement have been understand to use secure transport everywhere. Folks keep on saying HIPPA requires e2e but I've literally not seen anything that looks like that out there in the actual market for this - the enterprise paying the big bucks usually wants features that are incompatible with e2e as far as I can tell.

You mean, other than requirements that service provides track & preserve an audit trail for all data. ;-)

I believe this is a similar problem with financial trading systems with ETS.