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Back to Table of Contents

Back to IP Multimedia Subsystem (IMS)

Back to SBC as P-CSCF

Back to Emergency Registration

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In this section:

Table of Contents
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Steps to Handle Emergency Registration

To establish the emergency call;
:

  1. The
    Spacevars
    0product
    SBC determines if the UE registration is an Emergency Registration or not. This is indicated when the "sos" parameter is included in the contact header of the received REGISTER message and the equivalent configuration on the emergency call profile.
  2. SBC The
    Spacevars
    0product
    then treats this Emergency Registration as priority for CAC, in case the resources are exhausted.
  3. When SBC the 
    Spacevars
    0product
    sends on the emergency REGISTER message, the RPH is only included if it is configured to be included.
  4. When SBC the 
    Spacevars
    0product
    receives the 200 OK to REGISTER, the emergency registration is established. In IMS, a binding established through Emergency Registration is only used to make emergency calls.

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  1. If the PCRF lookup is rejected (and PCRF lookup is configured as required) then the SBC the 
    Spacevars
    0product
    sends a 380 status message with further information back to the UE
  2. If no route to the E-CSCF is possible, then based on configuration the SBC the 
    Spacevars
    0product
    may send a 380 status message with further information back to the UE.
  3. If an error response is received to an emergency session establishment, then based on configuration, SBC the 
    Spacevars
    0product
    may send a 380 status message with further information back to the UE.
  4. Relay of SIP status 424 back to the UE.

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