SIP

 

SIP UPDATE

Overview

The UPDATE method allows a UAC to update parameters of a session, such as the SDP and session timers.  

The UPDATE method allows a greater control over a SIP session including, but not limited to, the following parameters:

RFC

3311 SIP UPDATE Method

Benefits

Allows you to update parameters during a session when conditions change.

Configuration

The SIP UPDATE method is to be accepted by the IMG without user intervention, and therefore cannot be disabled. There is no configuration involved.

Related Topics

SIP UPDATE

 

SIP Session Timer

RFC

RFC 4028 Session Timers in the Session Initiation Protocol

Benefits

Provides a "keep alive" method for SIP Calls which allows you to better manage your resources in an abnormal situation such as network outage.

 

The RFC 3261 does not define a keep alive mechanism for the sessions it establishes.  The result is that an UA will not always be able to determine whether a session is still active.  For instance, when a remote party fails to send a BYE message at the end of a session, or when the BYE message gets lost due to network problems, the UA will not know that session has ended, thus will not release resource allocated for the session. To resolve this problem, the IMG supports the  keep alive mechanism for SIP sessions defined in RFC 4028 Session Timers in the Session Initiation Protocol (SIP).   

Configuration

SIP Session Timer

You configure the Session Timer in the SIP Session Timer pane. SIP Session Timer is enabled by default.

More Information

SIP Session Timer

 

SIP Busy Out

Brief Description

Set timers to determine if gateway is responsive or unresponsive.

RFC

RFC 3261 SIP: Session Initiation Protocol, Section 11.

Overview

The IMG can monitor the status of external SIP gateways by sending periodic SIP OPTIONS messages. If the gateway does not respond in a configured amount of time the IMG will mark the gateway as down and attempt to re-route the call to a different gateway.

Benefit

Allows you to monitor the status of external SIP gateways.

Configuration

SIP Profile

External Gateway

Related Topic

SIP Busy Out

 

SIP SUBSCRIBE/NOTIFY

Brief Description

The IMG accepts user agent subscription requests (SIP SUBSCRIBE method) and the ability to respond to those user agents with the appropriate DTMF digit events via the SIP NOTIFY method. Only DTMF-events are currently supported.

RFC

3265 Session Initiation Protocol (SIP)-Specific Event Notification

Benefits

Detect DTMF tones (##) in the middle of a call.

You can develop user-specific applications that reside on your network entity and have the ability to subscribe for event services supported by the IMG.  If the network entity wants the ability to detect an entered DTMF digit from the TDM-side of a call to the IP side of a call, the entity can subscribe to the IMG for these events and receive SIP NOTIFY events containing the digit event.

Configuration

SIP DTMF Support

Related Topic

SIP SUBSCRIBE/NOTIFY Method for DTMF

 

 

SIP PRACK

Brief Description

Improves network reliability and supports additional call flows.

RFCs

3262 - Reliability of Provisional Responses in the Session Initiation Protocol (SIP)

Overview

There are two types of responses defined by SIP that are provisional and final.  Final responses convey the result of the request processing and are sent reliably.    

There are certain scenarios in which the provisional SIP responses must be delivered reliably.  For example, in a SIP/PSTN inter-working scenario, a loss of 180 or 183 messages cannot be afforded. To solve this problem, the SIP PRACK method guarantees reliable and ordered delivery of provisional responses in SIP.

In addition, SIP PRACK provides further opportunities for SDP offer/answer exchange mode  because of its 3-way handshake design.

Configuration

SIP Profile

 

 

SIP Carrier Identification Code

Brief Description

Send Carrier Id Code (CIC) between SIP and SS7.

Benefits

Gives you the ability to send mixed traffic over a trunk group and improve call routing.

Overview

This feature enables the IMG to receive and transmit the Carrier Identification Code (CIC) parameter between the SIP network and SS7. The CIC parameter is a three- or four- digit code used in routing tables to identify the network that serves the remote user when a call is routed over many different networks. The CIC parameter is carried in SIP INVITE requests and maps to the SS7 Request.

Related Topic

SIP Carrier Identification Code

 

 

ISUP-OLI (ANSI Only)

The ISUP OLI (also know as II digits) parameter includes information that is used for carriers to determine the origin of a call. This information gets lost over SIP networks if not inter-worked properly. This feature allows carrying ANSI ISUP OLI Parameter from traditional TDM network into SIP and vice versa. This information is passed in the From: header of the INVITE message.

Related Topic

SIP ISUP OLI

 

 

ENUM

RFC

RFC 3764 enumservice registration for Session Initiation Protocol (SIP) Addresses-of-Record

Brief Description

Translates phone numbers to SIP addresses.

Benefits

Bypass PSTN for lower phone charges and faster connections.

Overview

The IMG supports ENUM E2U+sip  to resolve an ENUM telephone number into a SIP URI.

ENUM facilitates the interconnection of systems that rely on telephone numbers with those that use URIs to route transactions. E.164 is the ITU-T standard international numbering plan, under which all globally-reachable telephone numbers are organized.

Configuration

ENUM Servers

ENUM Server

Related Topic

SIP ENUM

 

 

SIP-Based Load Balancing

Brief Description

This feature allows you to distribute SIP traffic between IMGs configured as “SIP Servers” using virtual IP Addresses and a SIP load balancer.

Benefits

Improved scalability and fault tolerance.

Related Topics

SIP-Based Load Balancing

 

 

SIP CODEC Negotiation Priority

This feature allows you to configure whether the IMG or the remote gateway takes priority when selecting a codec.

Benefits

The feature gives you the flexibility to choose CODEC priority on either IMG or the far end gateway.   

Configuration

SIP Profile

You configure CODEC Negotiation Priority to either Local or Remote in the SIP Profile pane.

 

 

SIP REGISTER “Expires” Timer Control

This feature gives you the ability to control the expiration of a registration request sent from the IMG to a Remote SIP User Agent. The default is 3600 sec.

RFC

RFC 3261 SIP: Session Initiation Protocol

Configuration

External Gateway

You can change the default to a value between 10 and 7200 sec using the Registration Expiration Interval field in the External Gateway pane.

 

 

SIP 305 Redirect Response

Brief Description

The IMG now supports the 305 Use Proxy message.

Benefits

Enables re-direct to Proxy Server.

Related Topics

SIP 3XX Redirect Responses

 

 

SIP Call Hold

Brief Description

This feature allows the IMG to process a re-INVITE from a SIP endpoint that places a call on hold or releases a hold. This addition complements the current support for SIP Hold ( via 0.0.0.0 ip address) by supporting RFC 3398 section 9, allowing for the proper Interworking of hold information between SIP and SS7.

RFC

RFC 3398 Integrated Services Digital Network (ISDN) User Part (ISUP) to Session Initiation Protocol (SIP) Mapping (section 9)

Related Topic

SIP Call Hold.