In section 6.2.1 as well as other places, we allow setting arbitrary headers. What if the underlying telephony protocol allows multiple headers with the same name? I think the specification should address this in a couple of places:
Specifically allow for multiple headers with the same name.
Make some promise about the order of the headers being preserved at least as far as the delivery to the backend telephony protocol. I know that promising the same order in the SIP headers would be leaking SIP details into Rayo, but we should probably at least make some effort to guarantee order here (assuming order is ever significant).
In section 6.2.1 as well as other places, we allow setting arbitrary headers. What if the underlying telephony protocol allows multiple headers with the same name? I think the specification should address this in a couple of places: