Status-Line = SIP-Version SP Status-Code SP Reason-Phrase CRLF
例如： SIP/2.0 200 OK
header = "header-name" HCOLON header-value *(COMMA header-value)
例如：
From: Alice <sip:[email protected]>;tag=1928301774
CSeq: 314159 INVITE
Header fields can be extended over multiple lines by preceding each
extra line with at least one SP or horizontal tab (HT). The line
break and the whitespace at the beginning of the next line are
treated as a single SP character. Thus, the following are
equivalent:
Subject: I know you're there, pick up the phone and talk to me!
Subject: I know you're there,
pick up the phone
and talk to me!
The following groups of header field rows are valid and equivalent:
Route: <sip:[email protected]>
Subject: Lunch
Route: <sip:[email protected]>
Route: <sip:[email protected]>
Route: <sip:[email protected]>, <sip:[email protected]>
Route: <sip:[email protected]>
Subject: Lunch
Subject: Lunch
Route: <sip:[email protected]>, <sip:[email protected]>,
<sip:[email protected]>
