IMG 1010 - Overview of SIP
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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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Supported SIP Features
RFC | Description |
---|---|
2246 | Transport Layer Security (TLS) for SIP |
2327 | Session Description Protocol (SDP) |
2976 | SIP Info |
3240 | Internet media type message/sipfrag |
3261 | SIP: Session Initiation Protocol |
3262 | SIP PRACK |
3263 | Locating SIP servers for DNS lookup SRV and A records |
3264 | SDP Offer/Answer Model (Do not support multiple 'm' lines in SIP SDP) |
3265 | SIP Subscribe/Notify |
3311 | SIP Update |
3323 | SIP Privacy Header |
3325 | Asserted Identity |
3326 | SIP Reason Header |
3332 | M3UA Adaption Layer |
3372 | SIP for Telephones (SIP-T/SIP-I) |
3398 | ISUP/SIP Mapping |
3515 | SIP Refer |
3551 | Payload Type Support |
3578 | ISUP Overlap Signaling to SIP |
3581 | Symmetric Response Routing |
3666 | Call Flows - SIP to PSTN Dialing |
3711 | IP Media Layer Security Standard (RTP/RTCP) |
3725 | Third Party Call Control for SIP |
3764 | ENUM for SIP Address of Record |
3891 | SIP Replace Header |
3892 | SIP Referred by Mechanism |
4028 | SIP Session Timer |
4040 | Clear Channel Codec Support |
4244 | SIP History info (for call diversion) |
4568 | IP Signaling Layer Security Standard (RTP/RTCP) |
4904 | Trunk Group Parameter Support |
Basic Support
RFC 3261, SIP (Session Initiation Protocol)
Backward compatible with entities running RFC 2543
RFC 3581, Rport Extension Parameter in the Via Header
RFC 2327 SDP Support
RFC 3551 RTP Profile for Audio and Video Conferees with minimal control.
RFC 3666 Call Flows -- SIP to PSTN Dialing
RFC 3960 - Early Media and Ringing Tone Generation
Transmission Control Protocol Support (TCP/IP). Single or multi-socket use.
Reliable User Datagram Protocol (UDP) transport, with retransmissions
SIP Authentication and Outbound Registration. The IMG does not support inbound registration. Inbound Registration is not applicable with Media Gateways. For more information click on IMG 1010 - Authentication and Outbound Registration Link
Call Release Data in the Radius CDR (Software 10.5.0 +) Click IMG 1010 - Call Release Origin in CDR for more information
Vocoder Data in the Radius CDR (Software 10.5.0 +). Click IMG 1010 - RADIUS - Codec Info in CDR for more information
The IMG supports being a User Agent Client (UAC) or User Agent Server (UAS) and will inter-operate with SIP proxies.
Supports Early Media. Supports 180/183 Session Progress. Click IMG 1010 - Early Media for more information.
Can create multiple SIP profiles. A SIP Profile allows you to easily assign a number of SIP features to a Physical IMG. You create a SIP Profile and then assign profiles to a gateway in the External Gateway pane. See IMG 1010 - SIP Profiles link.
Supported Response Messages 1xx, 2xx, 3xx, 4xx, 5xx, 6xx
SIP Session Timer. Click on IMG 1010 - SIP Session Timer link for more information.
SIP Redirection. Click on IMG 1010 - SIP Redirect Server Support link for more information
SIP Transcoding. Click on IMG 1010 - Transcoding link for more information.
SIP Call Hold. Click on IMG 1010 - SIP Call Hold link for more information.
Supported Methods
SIP INFO Method - RFC 2976.  See IMG 1010 - SIP INFO Method - Overview for more information.
SIP INVITE/ReINVITE Method - RFC 3261 See IMG 1010 - INVITE Method for more information.
SIP SUBSCRIBE/NOTIFY Method. - RFC 3265. See IMG 1010 - SIP INFO Method - SUBSCRIBE-NOTIFY for more information.
SIP UPDATE Method - RFC 3311. See IMG 1010 - Update Method for more information
SIP OPTIONS (BUSY OUT) - RFC 3261. See IMG 1010 - SIP Options Keep Alive Overview - Busy Out link for more information
SIP REGISTER - Proxy Registration See IMG 1010 - SIP Proxy Handling and IMG 1010 - SIP Proxy link for more information (Outbound)
SIP CANCEL and BYE Methods - RFC3261
SIP PRACK (Provisional Response Acknowledgement) See IMG 1010 - SIP PRACK reliable provisional responses
SIP Extensions
SIP Diversion Header. See IMG 1010 - SIP Diversion Header link for more information
SIP Reason Header. See IMG 1010 - SIP Reason Header link for more information. (SIP to TDM and TDM to SIP)
SIP Privacy Header/Network Identity Header. RFC 3323 AND 3325. See IMG 1010 - SIP Privacy Overview and IMG 1010 - Configuring SIP Privacy for more information.
SIP Session Timers. RFC 2543 and 4028. See IMG 1010 - SIP Session Timer for more information.
SIP 3PCC. See IMG 1010 - SIP 3PCC - Third Party Call Control for more information.
Non-Standard Tags in From/To Header
Non-Standard Tags in R-URI
SIP History-Info Header Support - see IMG 1010 - SIP History-Info Header for more information
Routing/Call Handling
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
Media
Network Address Translation (NAT) Traversal. See IMG 1010 - Symmetric NAT Traversal for more information
Relay for Dual Tone Multi Frequency (DTMF) digits, including payload type negotiation (RFC 2833)
Codec Negotiation Priority. See IMG 1010 - SIP Codec Negotiation Priority Selection for more information
T.38 Fax support. See IMG 1010 - SIP Fax-Modem for more information.
Support for RFC 3550 (RTP: A Transport Protocol for Real-Time Applications) – Partially compliant.
If the remote side includes the fax maximum rate parameter in the SDP body of the INVITE message, the gateway returns the same rate in the response SDP.
Fax Modem Support. See IMG 1010 - SIP Fax-Modem for more information.
Receive and Transmit Gain control on per channel basis. See IMG 1010 - Channel Group
Supports G.729 AnnexB in SDP. See IMG 1010 - Vocoder Entry and IMG 1010 - Vocoder Information for more informationÂ
GSM Support for SIP (10.5.0 +). See IMG 1010 - Setting Host Flags, IMG 1010 - Vocoder Entry, and IMG 1010 - Vocoder Information links for more information.
G.726 Support for SIP (10.5.0 +). See IMG 1010 - Setting Host Flags, IMG 1010 - Vocoder Entry, and IMG 1010 - Vocoder Information links for more information.
Interworking
Basic Support:
SIP-T Support (Session Initiation Protocol for Telephones IETF) RFC 3372 - Â See IMG 1010 - Overview of SIP to SIP-T or SIP-I
SIP-I Support (Session Initiation Protocol for Telephones ITU ) RFC 3372 - See IMG 1010 - Overview of SIP to SIP-T or SIP-I
RFC 3666 Call Flows -- SIP to PSTN Dialing
Q.1912.5 Support for SIP to ISUP Interworking (10.5.0 +) RFC 3398.
ITX (SPIROU) support - See IMG 1010 - SPIROU-ITX in SIP INFO
ANSI ISUP Originating Line Info Support - See IMG 1010 - ISUP Originating Line Info Support - ANSI
SS7 to SIP Calling Party Category (CPC)
SIP Carrier Identification Code - See IMG 1010 - CIC and DAI Codes - SS7 ISUP to SIP
Customizable SIP-to-SS7 ISUP Cause Codes - See IMG 1010 - Customizing Cause Codes - SIP to SS7 ISUP
SIP UUI support - See IMG 1010 - SIP UUI Support
SIP to CAS
SIP
SIP 3xx Gateway Responses
SIP Diversion Header
SIP Trunk Group ID's
SIP Codec Negotiation
SIP Busy Out Modem BypasS
SIP-T
SIP-I
SIP over TLS
SIP Refer
SIP Refer for Call Transfer
SIP Dial Around Indicator Support
Generic Name Indicator (SIP to SS7)
M3UA Signaling Gateway for TCAP/SCCP
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