Is H.323 Annex E optional? H.225.0 says that an EP can indicate in an RRQ (and a GK, in an LCF) whether it supports H.323 Annex E (call-signaling over an unreliable channel), so Annex E is apparently optional. For example,
7.9.1/H.225.0v3: "supportsAnnexECallSignalling - If TRUE, this indicates that the sender of this message is capable of call signalling [sic] on an unreliable transport channel as described in H.323 Annex E."
However, H.225.0 also says that via an RCF or ACF a GK can force an EP to use Annex E. For example,
7.9.2/H.225.0v3: "useAnnexECallSignalling - If TRUE, this parameter indicates that the endpoint receiving this message shal [sic] use call signalling [sic] exclusively on an unreliable transport channel as described in H.323 Annex E when placing calls."
There is nothing in the Recommendations that requires a GK to abide by the EP's capabilities. Is this an oversight, or does the EP merely indicate in its RRQ a preference for supporting Annex E, and it must therefore support this Annex?