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SIP-T
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SIP-T (SIP for Telephones) and SIP-I (SIP with encapsulated ISUP) are mechanisms used to interconnect the PSTN with packet networks. SIP-T/SIP-I satisfies the interconnection from packet networks to PSTN through Encapsulation and Transparency. It is essential that SS7 information be available at the PSTN interconnection to ensure the transparency of features not supported in SIP. All SS7 information is available in its entirety to the SIP network across the PSTN-IP interface (IMG). SIP-T/SIP-I define SIP functions that map to ISUP interconnection requirements and transfer the information into the SIP Header for routing.
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Create the signaling object by Right-clicking on the Physical IMG object and select New Signaling.
Create the SIP Signaling object by Right-clicking on the Signaling object and select New SIP.
The SIP Signaling pane appears. In the Enable SIP-T field, select Yes to enable SIP-T . See below
In the SIP-T Behavior field, select Optional or Required from drop down menu. See screen capture below.
Optional:
Optional is the default. If Optional is selected and the far end does not support SIP-T/SIP-I, the call will not be released. When sending a response (18x, 200 OK, etc.) to an inbound SIP invite the IMG will include the SIP-T mime data if received in the inbound invite.
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If the ISUP MIME messages sent in the content header does not match the far end gateway, a new signaling variant will need to be created and then assigned to the SIP stack. The variant name in ClientView must match the version parameter in the SIP signaling from the remote gateway. This is accomplished in the SIP Entity Pane. See Below
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To create a custom SIP variant using the desired base variant and enter the exact name required by the far end right click on Dialogic IMG EMS and select New Signaling Variants.
Right click Signaling Variants and select New Signaling Variant. The Signaling Variant pane appears.
In the Variant Name field, select the field and enter the name for the variant expected by the far end.
In the Variant Type field select SIP-T
In the Base Variant field, select the base variant to use for this custom variant. See list above (Dialogic ISUP MIME Nomenclature) of variants that can be chosen from the drop down menu.
The Variant ID is automatically populated with the next ID. An ID can be manually selected by clicking on the Variant ID field and selecting the ID from the drop down list.
Once the variants are created they can be assigned to the SIP stack. To assign the signaling variant to an SIP stack follow the next few steps below.
Right-click the SIP signaling entry and select New SIP T Entity and the SIP-T Entity pane appears.
In the SS7 Stack field will be a drop down list of all the SS7 stacks configured. Select the SS7 stack from the drop down menu.
In the SIP Variant field will be a drop down list of all the Variants Created. Select a Variant from the Drop Down list
Related Topics
Additional Information
The SIP-I and SIP-T implementation on the IMG are similar. Information regarding SIP-T refers also to SIP-I.
When interworking SIP-T to ISUP, the outgoing IAM on the ISUP side will have the Called/Calling party numbers based on the information in the To/From Header in the SIP INVITE message. Everything else will be based on the encapsulated IAM in the SIP INVITE. By default, the To/From headers have precedence over the encapsulated Called/Calling Party Numbers.
By default, the SIP Headers are used for translation/routing. In the case of Transparent ISUP via SIP-T mode, translation is not applicable (see Transparent ISUP via SIP-T in the ISUP Group Pane: IMG 1010 - ISUP Group - ITU / ETSI , IMG 1010 - ISUP Group - ANSI , IMG 1010 - ISUP Group - JTISUP ).
SIP-T/SIP-I on the IMG follow RFC 3372 and Q.1912.5 specifications.
Based on RFC 3398, the APM (Application Transport Mechanism) message does not interwork into SIP.