asterisk users - Oct 2008 - Does asterisk 1.6 support an authname with a domain?

We need to include the domain information in the Authentication digest  
username SIP header field.

Using SIP/username[:password[:md5secret[:authname]]]@host[:port] in  
the dialplan breaks if authname needs username at domain.com, is there a  
way to specify this value from the dialplan?

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Eric Chamberlain