我正在阅读SIP RFC 3261。我没有区分sip uri和sips uri。有人可以提供帮助。
答案 0 :(得分：2)
来自rfc3261的第一个注释：
The format for a SIPS URI is the same, except that the scheme is
"sips" instead of sip.
第二个注释，我想你的问题可以在第26.2.2节（SIPS URI方案）中找到，即：它表示所有的跳都需要保护，最常见的是通过TLS链接。
When used as the Request-URI of a
request, the SIPS scheme signifies that each hop over which the
request is forwarded, until the request reaches the SIP entity
responsible for the domain portion of the Request-URI, must be
secured with TLS; once it reaches the domain in question it is
handled in accordance with local security and routing policy, quite
possibly using TLS for any last hop to a UAS. When used by the
originator of a request (as would be the case if they employed a SIPS
URI as the address-of-record of the target), SIPS dictates that the
entire request path to the target domain be so secured.
当“收件人”或“来自”标头中出现sips时，其他规则适用。例如，当To标题出现在To标题中时，它表示＆＃34; wish＆＃34;使用安全链接。在Request-URI中使用时，它必须是。
使用sips时，您可能还需要在Contact标头中使用sip。 sips URI最终将在Request-URI中用于对话框中的其他请求，因此您必须关心在Contact头中使用正确的sip / sips。