2010/11/26 Daniel-Constantin Mierla miconda@gmail.com:
For sure, Fromtag MUST be a header param and not a URI param (as Fromtag is defined to be a header param in RFC3261).
I am also positive about this, if there are no arrow brackets, then it is a header parameter. But I cannot say now exactly where is specified.
Section 20:
The Contact, From, and To header fields contain a URI. If the URI contains a comma, question mark or semicolon, the URI MUST be enclosed in angle brackets (< and >). Any URI parameters are contained within these brackets. If the URI is not enclosed in angle brackets, any semicolon-delimited parameters are header-parameters, not URI parameters.