1. Configuration Guide
  2. IMS Support
  3. 2629 - IR.92 Compliance via SIP 380 Response

2629 - IR.92 Compliance via SIP 380 Response

This feature furthers the Oracle Communications Session Border Controller’s compliance with GSMA's Voice over LTE specification (IR.92) to redirect VoLTE originated emergency calls to a circuit switched network.

When the Oracle Communications Session Border Controller receives an emergency call, which it can not complete, it returns a 380 (Alternative Service) response to the sender. Some examples of when the Oracle Communications Session Border Controller can not forward such an emergency call are:

  • The Next-hop does not exist to route the call via NMC means
  • The NSEP calls are rejected due to the Oracle Communications Session Border Controller hitting a load limit
  • The NSEP calls are rejected due to the target session agent exceeding constraints
  • The NMC treatment for the call is set to Reject

380 Response Format

The Oracle Communications Session Border Controller’s 380 SIP response to the sender includes:

  • Content-Type header field set to application/3gpp-ims+xml
  • P-Asserted-Identity header field set to the value of the SIP URI of the last entry on the Path header field value received during registration; It is the value of the SIP URI of the P-CSCF.
  • 3GPP IM CN subsystem XML body containing an <ims-3gpp> element with the "version" attribute will be set to "1" and with an <alternative-service> child element set to "alternative service"
    • a <type> child element set to emergency
    • a <reason> child element set to the value of configuration element send-380-response
    • an <action> child element set to emergency-registration

380 Response Example

SIP/2.0 380 Alternative Service
Via: SIP/2.0/UDP 192.168.15.2:5060;branch=z9hG4bK-23615-1-0
From: sipp <sip:911@192.168.15.2:5060>;tag=1
To: sut <sip:911@192.168.101.11:5060>
Call-ID: 1-23615@192.168.15.2
CSeq: 1 INVITE
Content-Type: application/3gpp-ims+xml
Content-Length: 209
P-Asserted-Identity: sip:911-44e2etbufgibf@172.16.101.11:5060
Reason: Q.850; cause=63
<?xml version='1.0' encoding="UTF-8"?>
<ims-3gpp version="1.0">
<alternative-service>
<type>emergency</type>
<action>emergency-registration</action>
<reason>sample reason</reason>
</alternative-service>
</ims-3gpp>

IR.92 Compliance Configuration

To configure the 380 SIP response for IR.92 compliance:

  1. In Superuser mode, type configure terminal and press Enter. 
    ORACLE# configure terminal
  2. Type session-router and press Enter to access the system-level configuration elements. 
    ORACLE(configure)# session-router
  3. Type sip-interface and press Enter. The system prompt changes to let you know that you can begin configuring individual parameters. 
    ORACLE(session-router)# sip-interface
ORACLE(sip-interface)#

    From this point, you can configure SIP interface parameters. To view all sip-interface parameters, enter a ? at the system prompt.

  4. If configuring an existing interface, enter the select command to select the interface.
  5. send-380-response—Enter a reason phrase enclosed in quotes to place in the reason tag of the <ims-3gpp> element in a 380 response for a failed-to-route emergency call.
  6. Type done and continue.