比如这样的
6 M& G4 z6 r: R7 {+ k3 j
- d2 f; I3 J) }) J% A% V: [' h
+ T+ ]& f2 d5 V4 j- G0 u6 sOPTIONS sip:nm SIP/2.0
% q5 u( P6 h6 k: QVia: SIP/2.0/TCP nm;branch=foo* T+ ~6 J' R/ \8 m8 Y9 E
From: <sip:nm@nm>;tag=root" Z) W: n0 B8 K- h: p
To: <sip:nm2@nm2>
( w$ _1 h$ {! C; c9 ?/ \3 jCall-ID: 50000+ I { S2 q# I& {6 M* \
CSeq: 42 OPTIONS8 Y- j0 g& K8 G9 j' I, F5 ~- i, C* \
Max-Forwards: 70
; b" s* S2 f4 r1 \$ fContent-Length: 0
6 {1 t2 e( P/ z, l) hContact: <sip:nm@nm>; ]5 F( c) _' n" L' ~% \
Accept: application/sdp: Z5 K3 H5 m, e+ A7 F) T
5 ]3 K1 {$ e7 k5 J
; G# J" h( {0 ]+ [+ m+ P3 K |