Subject: [SIP] Are there a few proxys in the same domain? In that case.......

From: 이희석 <[email-masked]>
Date: Tue, 30 Jan 2001 10:57:37 +0900

In that case,
"dragon" registered at "bbb.com" domain. 
So arnold sends a request(INVITE) to proxy 1 with request URI would be "sip:[email-masked]".

How does the proxy 1 search the next proxy server in them(proxy2,proxy3,proxy4) ?