Haha, I really like this. I would also like to try this configuraiton as a matter of interest, however this would not meet my client's requirements.I would really like the configuration to look like this, as described in a Cisco signallying document...
It may be uncouth to bump such an old topic, but I'm in the exact same scenario as you describe with a client. I'm using settings identical to yours for zone credentials, but it's still not properly passing authentication. Logins work if I set ever...