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P-Early-Media (RFC 5009) introduces the SIP P-Early-Media Header functionality. The P-Early-Media Header indicates media such as DTMF tones or pre-recorded announcements to be played prior to the call being answered. The P-Early-Media Header was added for this feature only. The IMG 2020 already supports Announcements - Pre-Call - Destination Number separately.
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The call flow diagram displays the aspects of precondition that the IMG 2020 supports. Below is an explanation to go along with the call flow above. The explanation assumes the IMG 2020 has been configured as described in the configuration section below. Basically, the SIP profile object linked to the incoming Leg A should have PRACK set to either Supported or Requiredand Required and the Precondition field of this object must be set to Required.
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The Call Flows below display the 3 typical call flows supported when F-6294 has been configured as described in the Configuration section below. Click on each link to access the individual call flows.
Configuration
When configuring the IMG 2020 for feature F-6294, there are three separate functions that need to be configured. The Precondition, Prack, and P-Early-Media functionalities must be configured and linked to the incoming leg. Configuring the combination of the Precondition, Prack, P-Early-Media functionality will allow the IMG 2020 to behave as displayed in the call flow diagrams described in the Call Flows section above. Since precondition is supported on the incoming leg but not on the outgoing leg, the Precondition, Prack, and P-Early-Media functionality only need to be configured on the incoming leg. Refer to the information below.
Before configuring this feature, verify that the required functionality described in the Basic Configurations topic has already been configured. Functionality such as the Physical Nodes, Logical Interfaces, Signaling, Profiles and IP Facilities have already been configured before proceeding. Also, refer to the Configure SIP (Single SIP IP) or Configure SIP (Multiple SIP IP) for information on configuring the SIP stack.
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Right click on the Profiles object and select New SIP Profiles. The SIP Profiles object is a container or parent object and no configuration is needed within this object. For more information on this object, refer to the SIP Profiles topic.
Right click on the SIP Profiles object and select New SIP Profile. Enter a name the describes the SIP Profile being configured. In this procedure, Inc_Precondition_Prof was entered.
In the PRACK Support field select Required from the drop down menu.
In the Precondition Support field, select Required from the drop down menu.
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Initially the Precondition Support field just under the PRACK Support field is shaded green and can't be modified. To be able to modify, the PRACK Support field just above it must first be modified to a value other than disabled. This was described in step 3 above. Once the PRACK Support displays something other than disabled, the Precondition Support field can then be modified. |
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Refer to the SIP Profile - SGP topic for information on configuring the remaining fields in this object.
Right click on the SIP Profile object just created and select New SIP Headers. In the P-Early-Media Support field select Enabled from the drop down menu.
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Refer to the SIP Profile - Headers topic for information on configuring the remaining fields in this object.
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Right click on the Dialogic object and select New External Network Elements. The External Network Elements object is a container object and no configuration is needed here. For more information on this object refer to the External Network Elements topic.
Right click on External Network Elements and select New External Gateways. The External Gateways object is a container object and no configuration is needed here. For more information on this object refer to the External Gateways topic.
Right click on External Gateways object and select New External Gateway. Enter a name that identifies this gateway. In this procedure the gateway was named Precondition_Inc_GW.
Select SIP from drop down menu in the Protocol field.
Select either Gateway IP Address or Gateway Host name from the Address Type field. In this procedure the IP Address will be how the IMG 2020 will communicate with external gateway.
Enter the IP address of the external gateway in the IP Address field.
Select the SIP Profile created earlier from the drop down menu of the Profile field.
Refer to the External Gateway topic for more information on configuring the remaining fields in this object.
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Right click on the Dialogic object and select New Routing Configuration. The Routing Configuration object is a container object and no configuration is needed here. For more information on this object refer to the Routing Configuration topic.
Right click on the Routing Configuration object and select New Channel Groups. The Channel Groups object is a container object for multiple channel groups. No configuration is needed here. For more information refer to the Channel Groups topic.
Right click on the Channel Groups object and select New Channel Group. In the Name field, either except the default name or enter a name that identifies the Channel Group being configured. In this procedure, the channel group was labeled Precondition_Inc_SIP.
Select SIP from the drop down menu in the Signaling Type field.
Select the Incoming and Outgoing IP Profile from drop down menu. Refer to the Channel Group topic for more information on configuring the remaining fields in this object.
Right click on the SIP Channel Group and select New IP Network Element. Select from drop down menu the gateway configured in the Associate SIP Profile with External Gateway section above. This will be the external gateway that the channel group being configured will communicate with. Refer to the IP Network Element topic for more information on this object.
Right click on the External Gateway object and select New Node Association. Select the Node from the drop down menu of the Node field.
Select the Packet Facility group that will be used to communicate between the IMG 2020 and the External Gateway.
Select the SIP Signaling IP Address from the Service IP address field. The IP address selected will control the Media Packet Facility group configured from step 8.
The Channel Groups object will now have an yellow exclamation point displayed in the configuration tree icon. The exclamation point indicates that the configuration has been created but not yet sent to the node. Click on the Channel Groups object and then click on the Download Resource Tables button in the Channel Groups object pane. The configuration will now get sent to the IMG 2020 node and the yellow exclamation point will change to a green check.
The feature has been configured. At this point routing can be configured to route the call through the IMG 2020
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