Page History

Overview

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

Figure 1: SBC SBC IMS Deployment - A-SBC as EATF Provisioning

EATF Call Flow

Figure 2: EATF call flow

he call flow description for Figure 2 is as follows:

1. The 

   Spacevars
   0 company

    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
• Configuring SBC Towards E-CSCF
• Configuring SBC Towards MSC

Global Configuration

• EATF Configuration
• Emergency Profile Configuration
• Trunk Group Towards E-CSCF
• Precondition Support
• Attaching EATF Profile to IPSP

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

Precondition Support_eatfPrecondition Support

Code Block
language none
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

anchor

Attaching EATF Profile to IPSP

1. Select "EATF" profile from the "Access Transfer Policy Type" option.
   Figure 3: Selecting EATF Profile

   
   

   
   

2. Attach the "EATF" profile to the Ip signaling profile of a Trunk Group.
   Figure 4: Attaching Attaching EATF profile to the IPSP Trunk group

   
   

Configuring SBC Towards E-CSCF

The following profiles are configured:

•  Transparency Profile 
  
• Zone Index profile 
• Ip Signaling Profile
• Sip Trunk Group 
  

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

Zone Index Profile_ecscfZone Index Profile

The following fields must be configured:

• Zone Index Profile
• Description
• Zone Index
  Figure 5:

PSX IPSP Zone Index Profile

Anchor

Ip Signaling Profile

Ip Signaling Profile_ecscfIp Signaling ProfileCommon

• Common Ip Attributes
• Relay Flags   
• Transparency Flags
  
• Egress Ip Attributes 
• Ingress Ip Attributes
  

Anchor

• Ip Attributes

_ecscf

• 
  

Common Ip Attributes_ecscfCommon 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
  Figure 6:

PSX IPSP Common Ip Attributes

AnchorRelay Flags_ecscf

Relay Flags_ecscfRelay 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.Figure 7: PSX

PSX IPSP Common Ip Attributes Relay Flags

AnchorTransparency Flags_ecscf

Transparency Flags_ecscfTransparency Flags

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

• Request-URI
  Figure 8: PSX

PSX IPSP Common Ip Attributes Transparency Flags

AnchorEgress Ip Attributes_ecscf

Egress Ip Attributes_ecscfEgress 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)Figure 9: PSX

PSX IPSP Common Ip Attributes Egress Ip Attributes

AnchorIngress Ip Attributes_ecscf

Ingress Ip Attributes_ecscfIngress Ip Attributes

The following "Ingress IP Attributes" must be enabled:

• 181 Supported (under Flags option)Figure 10: PSX

PSX IPSP Common Ip Attributes Ingress Ip Attributes

AnchorSip Trunk Group_ecscf

Sip Trunk Group

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.Figure 11:

PSX IPSP Sip Trunk Group towards E-CSCF
Image Modified

AnchorConfiguring SBC Towards MSC_ecscfConfiguring SBC Towards MSC_ecscf

Configuring SBC Towards MSC

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