AudioCodes Mediant 800B MSBR User Manual page 990

Parameter
Web: SBC Survivability
Registration Time
CLI: sbc-surv-rgstr-time
[SBCSurvivabilityRegistrationT
ime]
[SBCEnableAASTRASurvivabili
tyNotice]
User's Manual
the server sends a SIP 200 OK response. If the expiry time was
unchanged by the server, the device applies this feature and
changes the expiry time in the SIP 200 OK response before
forwarding it to the user; otherwise, the device does not change
the expiry time.
This feature is useful in scenarios where multiple users may
refresh their registration or subscription simultaneously, thereby
causing the device to handle many such sessions at a given time.
This may result in an overload of the device (reaching maximum
session capacity), thereby preventing the establishment of new
calls or preventing the handling of some user registration or
subscription requests. When this feature is enabled, the device
assigns a random expiry time to each user registration or
subscription and thus, ensuring future user registration and
subscription requests are more distributed over time (i.e., do not
all occur simultaneously).
The device takes any random number between 0 and the value
configured by this parameter, and then subtracts this random
number from the original expiry time value. For example, assume
that the original expiry time is 120 and this parameter is set to 10.
If the device randomly chooses the number 5 (i.e., between 0 and
10), the resultant expiry time will be 115 (120 minus 5).
The valid value is 0 to 20. The default is 10. If set to 0, the device
does not change the expiry time.
Notes:

The lowest expiry time that the device sends in the 200 OK,
regardless of the resultant calculation, is 10 seconds. For
example, if the original expiry time is 12 seconds and this
parameter is set to 5, theoretically, the new expiry time can be
less than 10 (e.g., 12 – 4 = 8). However, the expiry time will be
set to 10.

The expiry time received from the user can be changed by the
device before forwarding it to the proxy. This is configured by
the SBCUserRegistrationTime parameter.
Defines the duration of the periodic registrations between the
user and the device, when the device is in survivability state (i.e.,
when REGISTER requests cannot be forwarded to the proxy and
are terminated by the device). When set to 0, the device uses the
value set by the SBCUserRegistrationTime parameter for the
device's response.
The valid range is 0 to 2,000,000 seconds. The default is 0.
Enables the device to notify Aastra IP phones that the device is
currently operating in Survivability mode. When this occurs, the
Aastra IP phones display the message, "Stand Alone Mode" on
their LCD screens. Survivability mode occurs when connectivity
with the WAN fails and as a result, the device enables
communication between IP phone users within the LAN
enterprise.

[0] = Disable

[1] = Enable
When this feature is enabled and the SBC device is in
Survivability mode, it responds to SIP REGISTER messages from
the IP phones with a SIP 200 OK containing the following XML
990
Mediant 800B MSBR
Description
Document #: LTRT-12813