Registration Restriction Control; Deleting Registered Users; Media Handling - AudioCodes Mediant 4000 SBC User Manual

user from the database only when this additional time expires.

The graceful period is also used before removing a user from the registration
database when the device receives a successful unregister response (200 OK) from
the registrar/proxy server. This is useful in scenarios, for example, in which users (SIP
user agents) such as IP Phones erroneously send unregister requests. Instead of
immediately removing the user from the registration database upon receipt of a
successful unregister response, the device waits until it receives a successful
unregister response from the registrar server, waits the user-defined graceful time and
if no register refresh request is received from the user agent, removes the contact (or
AOR) from the database.
The device keeps registered users in its' registration database even if connectivity with the
proxy is lost (i.e., proxy does not respond to users' registration refresh requests). The
device removes users from the database only when their registration expiry time is reached
(with the additional grace period, if configured).

20.4.5 Registration Restriction Control

The device provides flexibility in controlling user registrations:

Limiting Number of Registrations: You can limit the number of users that can
register with the device per IP Group, SIP Interface, and/or SRD, in the IP Group, SIP
Interface and SRDs tables respectively. By default, no limitation exists.

Blocking Incoming Calls from Unregistered Users: You can block incoming calls
(INVITE requests) from unregistered users belonging to User-type IP Groups. By
default, calls from unregistered users are not blocked. This is configured per SIP
Interface or SRD. When the call is rejected, the device sends a SIP 500 (Server
Internal Error) response to the remote end.

20.4.6 Deleting Registered Users

You can remove registered users from the device's registration database through CLI:

To delete a specific registered user:
# clear voip register db sbc user <AOR of user – user part or
user@host>
For example:
# clear voip register db sbc user John@10.33.2.22
# clear voip register db sbc user John

To delete all registered users belonging to a specific IP Group:
# clear voip register db sbc ip-group <ID or name>
20.5

Media Handling

Media behavior includes anything related to the establishment, management and
termination of media sessions within the SIP protocol. Media sessions are created using
the SIP offer-answer mechanism. If successful, the result is a bi-directional media (RTP)
flow (e.g. audio, fax, modem, DTMF). Each offer-answer may create multiple media
sessions of different types (e.g. audio and fax). In a SIP dialog, multiple offer-answer
transactions may occur and each may change the media session characteristics (e.g. IP
address, port, coders, media types, and RTP mode). The media capabilities exchanged in
an offer-answer transaction include the following:

Media types (e.g., audio, secure audio, video, fax, and text)

IP addresses and ports of the media flow
User's Manual 424
Mediant 4000 SBC
Document #: LTRT-41729