Neither is proxy servers, DNS Servers, or Radius Servers (such as user manager). Those are applications on its own, hardly the function of a router
It's really a shame to see that MT won't support their very own products. 2.9.x is still the active version, 2.9.x is still supported. This attitute stinks.
Indeed, Proxy, DNS, Radius etc are not routing protocols as such, but without DNS there is no internet resolution, without radius there is no authentication, and all routers are proxy's in one way or another - that is all routers proxy data from one network to the next through a single point weather its specifically HTTP proxy or just a gateway.
As for support for telephony, I cannot remember where it is stated but i have read that it is about to be dropped before encountering this forum post. Still it should be supported until it is actually dropped altogether.