Paul,
Okay, but what if the EP does not indicate that it has this capability? 7.9.2/H.225.0v3 currently says that the EP _shall_ use an unreliable channel if in receipt of an RCF with useAnnexECallSignalling set to TRUE. Period. Regardless of whether the endpoint indicated the capability in its RRQ. The following would eliminate the ambiguity and possible misunderstanding:
7.9.2/H.225.0v3: "useAnnexECallSignalling - If TRUE and supportsAnnexECallSignalling was set to TRUE in the RRQ to which this message is in response, the endpoint receiving this message shall use call signaling exclusively on an unreliable transport channel as described in H.323 Annex E when placing calls."
Doesn't it mean that Gk can not adopt direct call routed model between endpoints. Consider when the remote endpoint is not Annex E Compliant. Now Ep1 sends call signalling messages *only* over UDP (after receiving useAnnexECallSignalling = TRUE in RCF). This direct routed call will not go through as Ep2 is not Annex E compliant.
Should Ep1 look into the callModel in ACF to figure out if it is Gk/direct routed call. If Gk routed and useAnnexECallSig = TRUE, do only UDP call signalling, and if direct routed, use Annex E Mixed TCP and UDP procedures ?
-M.Paul.