What Does SIP for Instant Messaging and and Presence Leveraging Extensions (SIMPLE) Mean?
Session Initiation Protocol for Instant Messaging and Presence Leveraging (SIMPLE) is an extension to the session initiation protocol (SIP) used to initiate and manage instant communication over a network or the Internet. SIMPLE is an open source protocol suite that is implemented or is part of a presence-based instant communication system.
Techopedia Explains SIP for Instant Messaging and and Presence Leveraging Extensions (SIMPLE)
SIMPLE is designed to provide information, alerts or notifications about a client’s presence and different modes of instant communication. The presence component of SIMPLE handles various processes native to SIP, including subscriptions, notifications and the Publication command, which each user agent sends to the server to relay their current information state.
SIMPLE provides instant messaging services in two different modes: Page Mode and Session Mode. Page Mode allows SIMPLE clients to exchange messages through the MESSAGE method, which is a SIP extension. In Session Mode, creating a session is required to exchange messages between user agent clients.