Do we need a standard for an RTT network gateway?
We've discussed RTT interoperability at some length, but this seems to have focussed on terminals.
In practice, RTT is likely to be handled within a given network according to some specific implementation, and this is unlikely to be the same implementation for everyone.
The way standards normally handle this type of thing in telecoms is to define a network-to-network interface (NNI) that can exist between two gateways rather than between two endpoints. If each implementation supports the standards NNI in their version of the gateway, you get global interoperability without imposing a single implementation on the industry.