IMG 1010 - Overview of SIP
SIP on an IMG
Session Initiation Protocol (SIP) is the Internet Engineering Task Force's (IETF's) standard for multimedia conferencing over IP. SIP is an ASCII-based, application-layer control protocol (defined in RFC 2543) that can be used to establish, maintain, and terminate calls between two or more end points. Like other VoIP protocols, SIP is designed to address the functions of signaling and session management within a packet telephony network. Signaling allows call information to be carried across network boundaries. Session management provides the ability to control the attributes of an end-to-end call whereby an IMG can be used as a Media Gateway to allow two separate networks to connect. The IMG supports SS7 to SIP, ISDN to SIP, CAS to SIP, SIP to SIP, and H.323 to SIP. Below is exemplary diagram of an IMG in a TDM to IP network.
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ENUM Support for SIP. RFC 3762 See IMG 1010 - SIP ENUM link for more information
SIP Load Balancing. See IMG 1010 - SIP-Based Load Balancing - Virtual IP Address for more information
SIP Trunk Group Selection / RFC 4904. See IMG 1010 - SIP Trunk Group Selection - 10.5.1_ER1 for more information
SIP Proxy Handling. See IMG 1010 - SIP Proxy Handling for more information.
SIP Redirect Server. See IMG 1010 - SIP Redirect Server Support and IMG 1010 - Supported 3xx Redirect Responses
SIP DNS Lookup. The IMG can route SIP traffic to a remote entity based on the IP Address or the Host Name. IMG 1010 - Configuring DNS for SIP
SIP DNS Redundancy. The IMG supports having multiple DNS servers for redundancy and reliability purposes. See IMG 1010 - DNS Server and IMG 1010 - DNS Client panes.
Re-origination. This feature allows you to limit the number of INVITE re-transmission attempts (1-5 attempts). The number configured supersedes the standard # of re-transmissions specified in RFC3261 (which is based on timers T1 and T2. The default is Re-transmit All. You enable this feature in the IMG 1010 - SIP Profile - 10.5.3.
SIP Gateway Busy Out. See IMG 1010 - SIP Options Keep Alive Overview - Busy Out for more information
DTMF out-of-band transfer using IMG 1010 - SIP INFO Method - DTMF and IMG 1010 - SIP INFO Method - SUBSCRIBE-NOTIFY
Representing trunk groups in SIP Uniform Resource Identifiers (URIs)
SIP PRACK in 1xx messages. See IMG 1010 - SIP PRACK reliable provisional responses
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