[Sip] sip grammar

[murali <muraliv@bharatmail.com>]

Hi,

	When i was going through the SIP Document: draft-ietf-sip-call-flows-05.txt
i came across a From Header which is like this

INVITE sip:+1-650-555-2222@ss1.wcom.com;user=phone SIP/2.0
Via: SIP/2.0/UDP ift.here.com:5060
From: sip:+1-303-555-1111@ift.here.com;user=phone
To: <sip:+1-650-555-2222@ss1.wcom.com;user=phone>
Call-ID: 1717@ift.here.com
CSeq: 17 INVITE
Contact: <sip:+1-303-555-1111@ift.here.com;user=phone>
Content-Type: application/sdp
Content-Length: 146

v=0
o=IFAXTERMINAL01 2890844527 2890844527 IN IP4 ift.here.com
s=Session SDP
c=IN IP4 iftmg.here.com
t=0 0
m=audio 3456 RTP/AVP 0
a=rtpmap:0 PCMU/8000
(Ref: 3.1.7 Successful SIP to SIP with re-INVITE) 

but Section 20.20 of RFC 3261 says that
"Even if the "display-name" is empty, the "name-addr" form MUST be 
used if the "addr-spec" contains a comma, question mark, or semicolon"

so, i'd like to know if the above usage is correct?
 In case it is correct how do i differentiate between the from parameters and URI-parameters as both are delimited by ;.
I mean to say that i can very well take that(user=phone) as generic parameter in from parameters instead of taking it as uri parameter

Thanks in advance
Murali



-------
Murali Voleti,
#503,Maheswari complex,
Masab Tank,
Hyderabad
Tele:(040) 6502272 ext:211

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