There have been several attempts to create a unified standard for instant messaging: IETF’s SIP (Session Initiation Protocol) and SIMPLE (SIP for Instant Messaging and Presence Leveraging Extensions), APEX (Application Exchange), Prim (Presence and Instant Messaging Protocol), the open XML-based XMPP (Extensible Messaging and Presence Protocol), and OMA’s (Open Mobile Alliance) IMPS (Instant Messaging and Presence Service) created specifically for mobile devices.
Most attempts at creating a unified standard for the major IM providers (AOL, Yahoo! and Microsoft) have failed, and each continues to use its own proprietary protocol for live chat /chatiquette. Live chat is part of live support system on the internet that needs unique live chat software.
However, while discussions at IETF were stalled, Reuters signed the first inter-service provider connectivity agreement on September 2003. This agreement enabled AIM, ICQ and MSN Messenger users to talk with Reuters Messaging counterparts and vice-versa. Following this, Microsoft, Yahoo! and AOL came to a deal where Microsoft’s Live Communication Server 2005 users would also have the possibility to talk to public instant messaging users. This deal established SIP/SIMPLE as a standard for protocol interoperability and established a connectivity fee for accessing public instant messaging clouds. Separately, on October 13, 2005 Microsoft and Yahoo! announced that by the 3rd quarter of 2006 they would interoperate using SIP/SIMPLE which was followed on December 2005 by the AOL and Google strategic partnership deal where Google Talk users would be able to talk with AIM and ICQ users provided they have an AIM account.
There are two ways to combine the many disparate protocols:
1. One way is to combine the many disparate protocols inside the IM client application.
2. The other way is to combine the many disparate protocols inside the IM server application. This approach moves the task of communicating to the other services to the server. Clients need not know or care about other IM protocols. For example, LCS 2005 Public IM Connectivity. This approach is popular in XMPP servers; however, the so-called transport projects suffer the same reverse engineering difficulties as any other project involved with closed protocols or formats.