AudioCodes Mediant 4000 SBC, User Manual

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CHAPTER 20 SIP Definitions
Mediant 4000 SBC | User's Manual
20 SIP Definitions
This section describes configuration of various SIP-related functionality.
Configuring Registration Accounts
The Accounts table lets you configure up to 625 Accounts. An Account defines information for
registering and authenticating (digest) IP Groups (e.g., IP PBX) with a "serving" IP Group (e.g.,
ITSP).
The device initiates registration with a "serving" IP Group on behalf of the "served" IP Group.
Therefore, Accounts are typically required when the "served" IP Group is unable to register or
authenticate itself for whatever reason. Registration information includes username, password,
host name (AOR), and contact user name (AOR). The device includes this information in the
REGISTER message sent to the serving IP Group. Up to 10 Accounts can be configured per
"served" IP Group. A IP Group can register to more than one IP Group (e.g., multiple ITSPs). This
is done by configuring multiple entries in the Accounts table for the same served IP Group, but with
different serving IP Groups, username/password, host name, and contact user values.
Authentication is typically required for INVITE messages sent to the "serving" IP Group. If the
device receives a SIP 401 (Unauthorized) in response to a sent INVITE, the device checks for a
matching "serving" and "served" entry in the Accounts table. If a matching row exists, the device
authenticates the INVITE by providing the corresponding MD5 authentication username and
password to the "serving" IP Group.
If the Account is not registered and the device receives a SIP dialog request (e.g., INVITE) from the
Served IP Group, the device rejects the dialog and sends the Served IP Group a SIP 400 (Bad
Request) response. An Account that is not registered can be due to any of the following reasons:
■ You have unregistered the Served IP Group by clicking the Register button (discussed later in
this section).
■ The Serving IP Group has rejected the registration.
However, if the Account is not registered and you have enabled the Registrar Stickiness feature
('Registrar Stickiness' parameter is configured to
Enable ) or dynamic UDP port assignment feature
('UDP Port Assignment' parameter is configured to Enable ) and the device receives a SIP dialog
request (e.g., INVITE) from the Served IP Group, the device rejects the dialog and sends the
Served IP Group a SIP 500 (Server Internal Error) response. In this scenario, the Account can be
not registered due to any of the reasons listed previously or for the dynamic UDP port assignment
feature, there is no available port for the Account (port used for interfacing with the Serving IP
Group).
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