比如这样的- B# q* @- W4 T- x* z- d; S0 d
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OPTIONS sip:nm SIP/2.0
& E" J; p7 g3 Q! {; _, ]# |2 l# Y) \Via: SIP/2.0/TCP nm;branch=foo
1 l3 M; ?: S* s& K" g: O5 X }From: <sip:nm@nm>;tag=root* m- M/ a) h) E: b$ P( g
To: <sip:nm2@nm2>$ U) R: q1 {7 o
Call-ID: 50000
/ w6 b: X: o6 ]& [7 ~$ B. ^( n$ }CSeq: 42 OPTIONS
( S1 Q' V. x( |1 _% \8 L; XMax-Forwards: 70
" W* k* @9 j0 qContent-Length: 00 _0 z, }1 D& d4 y
Contact: <sip:nm@nm>6 D' g- h; Q# M* l4 a' K
Accept: application/sdp/ r" G( u$ J3 X% X
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