High Probability of Completion (HPC) features comprise a set of functionalities that provide an enhanced probability of call completion to authorized Government Emergency Telecommunications Service (GETS) and Wireless Priority Service (WPS) users during network stress and/or congestion. Include Page |
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| _GETS_Use_Note |
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| _GETS_Use_Note |
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The SBC supports the following HPC capabilities: - Identification of an HPC call based on the presence of either a GETS-Access Number (AN), or GETS-Number Translation (NT) string.
- Rejection of a call based on the presence of GET-Feature Code (FC) string.
- Identification of an HPC call based on the code point in the Calling Party Category (CPC) parameter of the ISUP MIME.
- Prioritization or rejection of a call based on Resource-Priority Header (RPH) r-values in an initial INVITE. The SBC also processes mid-call RPH.
- Generation of an RPH for inclusion in egress SIP messages.
- Support for early or late HPC call classification.
- Detection and logging of error conditions.
- HPC Call Admission Controls - ingress CAC for early HPC classified calls, and egress CAC treatment for early and late HPC classified calls.
- Call Queuing, if an HPC call request fails to get a resource it is queued; when the required resource is available, the processing resumes.
- Exemption of HPC messages from congestion control.
- DSCP marking and priority treatment for HPC packets - SIP, Diameter and Media packets.
- High Priority Media Port Range (HPMPR) - packets received on ports in (HPMPR) are prioritized.
- Statistics and alarms for monitoring HPC traffic.
There are two methods in HPC call classification: - Early HPC classification—An HPC call is recognized based on the received SIP RPH content in the incoming INVITE or the code point in Calling Party's Category (CPC) parameter of the ISUP-MIME. For ANSI, the CPC parameter is National Security/Emergency Preparedness (NS/EP) and for ITU, the CPC parameter isInternationalEmergency Preference Scheme (IEPS).
- Late HPC classification—An HPC call can also be recognized by the PSX during analysis of the Called Party Number.
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| For more information, refer to: |
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| Preferential servicing of HPC calls is conditional on the installation of NW-HPC license on the EMS. For more information on EMS licenses, refer to the EMS documentation Licensed Applications and Features. |
The SBC supports the use of different Differentiated Services Code Point (DSCP) marking for signaling traffic that is associated with HPC and non-HPC calls. To support different DSCP marking for HPC and non-HPC calls in a SIP trunk group, the dscpValue parameter in the HPC profile configuration marks HPC calls and the DSCP configuration in the SIP signaling port marks non-HPC calls. The DSCP value configured in the HPC profile takes precedence over the DSCP value configured in the SIP signaling port and applies to all outbound traffic (IPv4 and IPv6) associated with HPC calls. The outbound SIP signaling messages associated with HPC and non-HPC calls are marked with the DSCP value configured in the SIP signaling port when the hpcCallProfile is not configured in a SIP trunk group. Note |
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| Setting the DSCP on the UDP or TCP network socket is a system call, which impacts the system performance if the DSCP frequently switches between HPC and non-HPC calls. |
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| This feature only applies to HPC calls over UDP transport. This feature does not apply to TCP transport since TCP is byte stream oriented and does not preserve message boundaries. |
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