SIP Network Devices Made Simple - SIP Walks & Talks

An Animated Explanation of key Session Initiation Protocol Servers and Proxies
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The nomenclature for devices in a SIP network generally consists of: UA-User Agent is a logical (not necessarily physical) function that initiates or responds to SIP communications. A UA can be either a client or server that maintains a "session" status in the SIP communications. UAC-User Agent Client is also a logical and physical function that initiates or responds to SIP communications.
SIP Location Server - provides information (database) about a caller's possible locations to redirect and proxy servers and may be co-located with a SIP server. UAS-User Agent Server is a logical and physical function that initiates or responds to SIP communications. Proxy Server acts like (hence the term proxy) as an intermediate server that is responsible for forwarding SIP requests to the destination UAS-User Agent Server on behalf of the UAC-User Agent Client. Redirect Server is an optional SIP component that does not route SIP messages.
A Redirect Server returns a redirect (via 3xx class address change in routing) to UA-User Agent or UAC-User Agent Client for direct routing (SIP is designed for end-to-end signaling without intervention by a server). Registrar Server is a user agent server that accepts SIP REGISTER requests and updates. B2BUA-Back-to-Back User Agent acts like a central PBX connection server processing incoming and outgoing messaging between other user agent servers. The B2BUA maintains "answer supervision" (overseeing) the dialog state and participates in all dialog communications.

This presentation is also included in TMC University special course on Microsoft OCS-Office Communications Server at ITexpo.com. For more go here: http://www.tmcnet.com/voip/conference/west-08/tmc-university-microsoft-ocs.htm

This presentation is also included in online/onsite courses SIP 2.0c and for OCS-101 Office Communications Server per person (volume and site license discounts available). Discounts are also available to members of the SIP Forum and MS Partners. For customizing, special discounts, website animations, technical/sales training, technical writing and other services, go to http://www.techtionary.com or please call Tom Cross at 303-594-1694 or cross@gocross.com.