How does GKs authenticate each other?, As yet, they don't... and furthermore, how does a GK authenticate an H.323 entity under its zone so that it can be sure it is talking with the entitiy it claims to be?, I haven't seen anything on this on the proposals for Anex G I've read. ...however, in version 2 of H.225.0 all RAS messages may contain authentication tokens. H.235 specifies the framework within which this works, although it does not prescribe any particular authentication mechanism. I would expect similar authentication tokens to appear in any inter-gatekeeper or inter-administrative-domain messages where authentication is required.

Regards, Chris -- Dr Chris Purvis - Senior Development Engineer, WAVE CC Software Madge Networks Ltd, Wexham Springs, Framewood Road, Wexham, Berks. Phone:+44 1753 661359 email: cpurvis@madge.com