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Voice Feature Guide 01

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Huawei uses machine translation combined with human proofreading to translate this document to different languages in order to help you better understand the content of this document. Note: Even the most advanced machine translation cannot match the quality of professional translators. Huawei shall not bear any responsibility for translation accuracy and it is recommended that you refer to the English document (a link for which has been provided).
Emergency Call

Emergency Call

The MA5600T/MA5603T/MA5608T identifies emergency calls according to emergency call digitmaps and ensures successful emergency calls by reserving digital signal processing (DSP) resources and implementing CPU overload control (OLC).

Definition

An emergency call is a kind of voice service initiated by a user using a terminal in case of emergencies. Generally, a fixed emergency call number is used within a country or region, for example, 911 in America and 110/119 in mainland China. When a user dials such a number, the system identifies the call as an emergency call, implements special processing on the call, and sends a request for routing the call to a specific emergency call center.

Device Implementation

The MA5600T/MA5603T/MA5608T identifies emergency calls according to emergency call digitmaps and ensures successful emergency calls by reserving DSP resources and implementing CPU OLC.

Digitmap

A digitmap is a set of digit collection descriptors. It is a dialing scheme resident in the MSAN and is used for detecting and reporting digit events received on a termination.

An emergency call digitmap is a dialing scheme for emergency calls. Using such digitmaps, emergency calls can be distinguished from common calls. The MSAN and core network devices, such as SoftX3000 or IMS, will then take protective measures for these emergency calls.

The MA5600T/MA5603T/MA5608T supports manual configuration of emergency call digitmaps, meeting requirements in different countries or regions.
NOTE:

Digitmap configuration is complex because a digitmap is constituted by characters that have specific meanings and usage. Such information is defined in protocols and will not be detailed in this topic. It is recommended that you refer to the digitmap description in ITU-T H248.1 (applicable to the H.248 protocol) or ITU-T SIP.1 (applicable to the SIP protocol) before configuring a digitmap.

DSP Resource Reservation

DSP resources are the most important voice resources in VoIP and are used for converting TDM service flows into IP service flows. To ensure a high success rate of emergency calls, the system reserves some DSP resources (which are configurable) for callers and callees of emergency calls.

Figure 1-168 illustrates how the system reserves DSP resources for callers of emergency calls.

Figure 1-168 Reserving DSP resources for callers of emergency calls

Figure 1-169 illustrates how the system reserves DSP resources for callees of emergency calls.

Figure 1-169 Reserving DSP resources for callees of emergency calls

CPU OLC

CPU OLC prevents exhaustion of equipment CPU resources. It protects equipment from service interruption or NMS management failure that is triggered by CPU overload in case of heavy traffic. CPU OLC also ensures to a certain extent the quality of high priority services when the system is overloaded.

The system employs CPU OLC for callers and callees of emergency calls, ensuring a high success rate of emergency calls.

Figure 1-170 illustrates how the system implements CPU OLC for callers of emergency calls.

Figure 1-170 Implementing CPU OLC for callers of emergency calls

Figure 1-171 illustrates how the system implements CPU OLC for callees of emergency calls.

Figure 1-171 Implementing CPU OLC for callees of emergency calls

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Updated: 2019-02-22

Document ID: EDOC1100067358

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