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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).
Call Flow of ISDN

Call Flow of ISDN

ISDN System Structure

Figure 1-109 shows the ISDN system structure.

Figure 1-109 ISDN System Structure

The ISDN users include the BRA users and PRA users.
  • The BRA users can connect the ISDN telephone with the NT1 directly, or connect the common telephone through the TA. On the MG side, the BRA users access to the network through the BRA port. Connect the NT1 and MG with the ordinary telephone line.
  • The PRA users access the network through the E1 port with the PBX. Connect the PBX and the gateway with the E1 cable.

ISDN Call Control Process

Figure 1-110 shows the ISDN call control process.

Figure 1-110 ISDN call control process

The call process includes two sections: call setup and call disconnection.

  • The call setup process is as follows:

    1. The host hooks off and initiates a call setup.
    2. The softswitch responds "SETUP_ACK", and applies more call information, such as the called number.
    3. The calling party dials, and the number is carried by the primitive IMFORMATION to the softswitch.
    4. The softswitch responds "CALL PROCEEDING", and the call is setting up.
    5. The softswitch applies sending setup to the called party to set up a call.
    6. After receiving the call, the called party starts ringing and sends "ALERTING". If the "ALERTING" reaches the calling party, the call is connected.
    7. The called party hooks off and sends "CONNECT". If the "CONNECT" reaches, the call is connected.
    8. The calling party responds "CONNECT_ACK". The call setup is complete.
  • The call disconnection process is as follows:

    1. One party hooks on, and sends "DISCONNECT".
    2. The softswitch sends "DISCONNECT" to the other party, and sends "RELEASE" to the party who hooks on.
    3. The party who hooks on finishes the call disconnection, and sends "RELEASE_COMPLETE" to the softswitch.
    4. After receiving the disconnection, the other party sends "RELEASE" to the softswitch.
    5. The softswitch responds "RELEASE_COMPLETE".
    6. The other party hooks on, and sends "DISCONNECT". The call disconnection is complete.
Updated: 2019-02-22

Document ID: EDOC1100067358

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