________________________________________
From: [email protected] 
[[email protected]] On Behalf Of Alex Bakker 
[[email protected]]

To: <sip:192.168.0.247:5060;user=phone>
_______________________________________________

To summarize and extend what others have said:

This form is syntactically correct.

The grammar for the headers is in RFC 3261 section 25.1.  But beware that in 
any place where the BNF is "( name-addr / addr-spec )", the inherent ambiguity 
in parsing is resolved by this part of section 20.10:

   When the header field value contains a display name, the URI
   including all URI parameters is enclosed in "<" and ">".  If no "<"
   and ">" are present, all parameters after the URI are header
   parameters, not URI parameters.  The display name can be tokens, or a
   quoted string, if a larger character set is desired.

   Even if the "display-name" is empty, the "name-addr" form MUST be
   used if the "addr-spec" contains a comma, semicolon, or question
   mark.  There may or may not be LWS between the display-name and the
   "<".

   These rules for parsing a display name, URI and URI parameters, and
   header parameters also apply for the header fields To and From.

The conventional "user=phone" parameter is a URI parameter and so in this 
context should appear inside the <...>, as it is in your example.  See section 
19.1.1.

The URI does not contain a user-part, so the user=phone parameter is 
semantically invalid, since the 'user' parameter describes the user-part.

Since the "To" header value is mostly documentation, the SIP request should not 
be rejected because of this semantic error; rather the semantic error should be 
ignored.  If some downstream processing needs to act on the URI, the 'user' 
parmeter should be ignored.

Dale

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