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Overview

IMPORTANT

The Transparency Profile is the recommended method of configuring transparency on the SBC Core for new deployments as well as when applying additional transparency configurations to existing deployments. Do not use IP Signaling Profile flags in these scenarios because the flags will be retired in upcoming releases.

Refer to the SBC SIP Transparency Implementation Guide for additional information.

At a high level, the functions performed by the EATF are:

  • The EATF provides IMS-based mechanisms for enabling service continuity of IMS emergency sessions. It is a function in the serving (visited if roaming) IMS network, which provides the procedures for IMS emergency session anchoring and PS to CS Access Transfer.
  • The EATF acts as a routing B2BUA, which invokes third party call control (3pcc) to enable access transfer.
  • The EATF performs the session continuity when the access transfer request indicated by the E-STN-SR is received.

Deployment Scenario

SBC IMS Deployment - A-SBC as EATF Provisioning

Call Flow

EATF call flow

he call flow description for Figure 2is as follows:

  1. The Ribbon SBC, acting as an A-SBC and EATF, receives INVITE request from UE.
  2. The SBC forwards the INVITE to the same P-CSCF to whom the original REGISTER is sent.
  3. The P-CSCF forwards to the E-CSCF.
  4. The E-CSCF invokes the EATF so that the call is anchored for a future handover. The E-CSCF adds two Route headers – one pointing to EATF and another pointing itself (E-CSCF).
  5. The EATF deletes the top route header pointing to itself and anchors the emergency session.
  6. The EATF loops back the call towards the E-CSCF based on the top route header (that points E-CSCF) from the remaining route header list.
  7. The E-CSCF forwards it to the PSAP.

    In the remaining steps, the 200 OK SIP response is forwarded as appropriate.

Configuration

Global Configuration

EATF Configuration

set global signaling srvcc eStnSr +1-237-555-5555 callLingerTimer 32
set addressContext default zone ZONE_CORENW srvcc eatf enabled
set addressContext default zone ZONE_CORENW dialogTransparency disabled
set addressContext default zone ZONE_CORENW disableZoneLevelLoopDetection enabled

Emergency Profile Configuration

set profiles services sipResourcePriorityHeaderProfile "RPH-1" rphEmergencyMatchingConfig "esnet" "1" 
commit
set profiles services sipResourcePriorityHeaderProfile "RPH-1" sendEgressRphForEmergency esnet 1
commit
set profiles services emergencyCallProfile "EMG-ECSCF" resPriorityHeaderProfile "RPH-1" sosInContactOfRegister "enable" 
commit
set profiles services emergencyCallProfile EMG-ECSCF prefix 911
comm
set profiles services emergencyCallProfile EMG-ECSCF urnPrefix service:sos.fire
comm
set profiles services emergencyCallProfile EMG-ECSCF sosInContactOfRegister enable
comm

Trunk Group Towards E-CSCF

set addressContext default zone ZONE_ECSCF sipTrunkGroup TG_TOWARDS_ECSCF signaling registration requireRegistration required-nonpriority useRUriForRegisterRouting enabled
set addressContext default zone ZONE_ECSCF sipTrunkGroup TG_TOWARDS_ECSCF signaling prefRequireTransparency "enabled" deRegParentWithChildDereg "enabled" validateAor "enabled" condIncMethInAllowHdr "enabled" usePsxRouteForEmergencyCall "enabled"
set addressContext default zone ZONE_ECSCF sipTrunkGroup TG_TOWARDS_ECSCF callRouting useRouteSet rcbNextHopAndStored
set profiles signaling ipSignalingProfile IPSP_PCSCF egressIpAttributes privacy transparency enable
set addressContext default zone ZONE_ECSCF sipTrunkGroup TG_TOWARDS_ECSCF services emergencyCallProfile EMG-ECSCF

Precondition Support

set addressContext default zone ZONE_CORENW sipTrunkGroup TG_TOWARDS_IMSCORE services preconditions transparent
set addressContext default zone ZONE_ECSCF sipTrunkGroup TG_TOWARDS_ECSCF services preconditions transparent
commit

Attaching EATF Profile to IPSP

  1. Select "EATF" profile from the "Access Transfer Policy Type" option.

    Selecting EATF Profile

  2. Attach the "EATF" profile to the Ip signaling profile of a Trunk Group.

    Attaching EATF profile to the IPSP Trunk group

Configuring SBC Towards E-CSCF

The following profiles are configured:

Transparency Profile

set profiles services transparencyProfile TRANS_PROF_ECSCF sipHeader To
set profiles services transparencyProfile TRANS_PROF_ECSCF sipHeader From
set profiles services transparencyProfile TRANS_PROF_ECSCF sipHeader Path
set profiles services transparencyProfile TRANS_PROF_ECSCF sipHeader Accept
set profiles services transparencyProfile TRANS_PROF_ECSCF sipHeader Reason
set profiles services transparencyProfile TRANS_PROF_ECSCF sipHeader Server
set profiles services transparencyProfile TRANS_PROF_ECSCF sipHeader Warning
set profiles services transparencyProfile TRANS_PROF_ECSCF sipHeader Call-Info
set profiles services transparencyProfile TRANS_PROF_ECSCF sipHeader Alert-Info
set profiles services transparencyProfile TRANS_PROF_ECSCF sipHeader Error-Info
set profiles services transparencyProfile TRANS_PROF_ECSCF sipHeader User-Agent
set profiles services transparencyProfile TRANS_PROF_ECSCF sipHeader Referred-By excludedMethods register,subscribe,info,publish,message,options,update,bye
set profiles services transparencyProfile TRANS_PROF_ECSCF sipHeader Request-URI
set profiles services transparencyProfile TRANS_PROF_ECSCF sipHeader Accept-Language
set profiles services transparencyProfile TRANS_PROF_ECSCF sipHeader P-Called-Party-Id
set profiles services transparencyProfile TRANS_PROF_ECSCF sipHeader Require
set profiles services transparencyProfile TRANS_PROF_ECSCF sipHeader Proxy-Require
set profiles services transparencyProfile TRANS_PROF_ECSCF sipHeader Security-Client
set profiles services transparencyProfile TRANS_PROF_ECSCF sipHeader Security-Verify
commit
set profiles services transparencyProfile TRANS_PROF_ECSCF sipMessageBody application/pidf+xml excludedMethods register,invite,subscribe,info,publish,message,options,update,bye
set profiles services transparencyProfile TRANS_PROF_ECSCF sipMessageBody application/pidf+xml
set profiles services transparencyProfile TRANS_PROF_ECSCF sipMessageBody application/rlmi+xml
set profiles services transparencyProfile TRANS_PROF_ECSCF sipMessageBody message/external-body
set profiles services transparencyProfile TRANS_PROF_ECSCF sipMessageBody application/pidf+xml
set profiles services transparencyProfile TRANS_PROF_ECSCF sipMessageBody application/cpim-pidf+xml
set profiles services transparencyProfile TRANS_PROF_ECSCF sipMessageBody application/pidf-diff+xml
set profiles services transparencyProfile TRANS_PROF_ECSCF sipMessageBody application/dialog-info+xml
set profiles services transparencyProfile TRANS_PROF_ECSCF sipMessageBody application/simple-filter+xml
set profiles services transparencyProfile TRANS_PROF_ECSCF sipMessageBody application/resource-lists+xml
set profiles services transparencyProfile TRANS_PROF_ECSCF sipMessageBody application/conference-info+xml
set profiles services transparencyProfile TRANS_PROF_ECSCF sipMessageBody application/simple-message-summary
commit
set profiles services transparencyProfile TRANS_PROF_ECSCF state enabled
commit
set addressContext default zone ZONE_ECSCF sipTrunkGroup TG_TOWARDS_ECSCF services transparencyProfile TRANS_PROF_ECSCF
commit

Zone Index Profile

The following fields must be configured:

  • Zone Index Profile
  • Description
  • Zone Index

PSX IPSP Zone Index Profile

Ip Signaling Profile

Common Ip Attributes

The following "Common IP Attributes" must be enabled in PSX under "IP SIGNALING PROFILE":

  • Disable Host Translation
  • End to End BYE
  • End to End RE-INVITE
  • End to End UPDATE
  • End to End PRACK
  • Insert Peer Address As Top Route Header
  • No Port Number 5060
  • ReQuery PSX on REGISTER Refresh
  • Store P-Charging-Vector
  • Validate Access Nw Info Header

PSX IPSP Common Ip Attributes

Relay Flags

The following "Relay Flags" must be enabled under "Ip Signaling profile":

  • Conference Event Package
  • Dialog Event Package
  • Info
  • Message
  • Options
  • PUBLISH
  • REFER
  • Reg Event Package
  • Status Code 4XX-6XX
  • Select Reject the REFER request if no match is found from Refer To Header Relay option.

PSX IPSP Common Ip Attributes Relay Flags

Transparency Flags

The following "Transparency Flag" must be enabled under "Ip Signaling Profile":

  • Request-URI

PSX IPSP Common Ip Attributes Transparency Flags

Egress Ip Attributes 

The following "Egress IP Attributes" must be enabled:

  • Select SIP Only from IP Protocol Type.
  • Disable 2806 Compliance (under Flags)
  • Transit PAI From Unregistered Peer (under Flags)
  • Add Loop Back Route Header (under Flags)
  • Select Include npdi from NPDI Options (under Number Portability Attributes option).
  • Select P-Preferred-ID from Privacy Information (under Privacy option).
  • Merge Received Contacts with Existing Contacts (under Redirect)
  • Select Include None from Include Charge Information option (under SIP Headers and Parameters)
  • Select Original Called Number (OCN) from SIP TO Header Mapping option (under SIP Headers and Parameters)
  • Include CPC Information (under SIP Headers and Parameters > Flags)
  • Transparency For Destination Trunk Group Parameter (under SIP Headers and Parameters > Flags)
  • End To End Ack (under SIP Headers and Parameters > Flags)
  • Diversion (under SIP Headers and Parameters > Call Forwarding)
  • Select Retry Without ETS from the Action For ETS 400 Responses With 417 Reason Code drop-down box (under SIP RPH ETS)
  • Set ETS Default Priority Value as 0  (under SIP RPH ETS)

PSX IPSP Common Ip Attributes Egress Ip Attributes

Ingress Ip Attributes

The following "Ingress IP Attributes" must be enabled:

  • 181 Supported (under Flags option)

PSX IPSP Common Ip Attributes Ingress Ip Attributes

Sip Trunk Group

The following profiles/fields must be enabled:

  • Zone Index Profile
  • IP Signaling Profile
  • Feature Control Profile
  • Signaling Profile
  • SIP Domain
  • IP Version Preference
  • Use IPTG Routing (Hop By Hop Routing) For Ingress (Ingress > Flags)
  • Do Not Use For Fallback Bearer Capability (Egress > Flags)
  • IP Peer Supported (Egress > IPTG)
  • Egress IP Signaling Profile (Egress > IPTG)
  • Select Traffic Management Options from Trunk Group Reserved Level 1 and Trunk Group Reserved Level 2.
  • Select Services as Not Screened.

PSX IPSP Sip Trunk Group towards E-CSCF

 

Configuring SBC Towards MSC

For configuring SBC towards MSC, refer to Configuring SBC Towards MSC.