AudioCodes Mediant 800B User Manual page 1304

Parameter
SBC Survivability Registration Time
configure voip > sbc settings > sbc-surv-
rgstr-time
[SBCSurvivabilityRegistrationTime]
configure voip > sbc settings >
User's Manual
Mediant 800B Gateway & E-SBC
Description
successful registration or subscription, 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 the parameter, and then
subtracts this random number from the original expiry
time value. For example, assume that the original
expiry time is 120 and the 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.
Note:

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 the 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
1304 Document #: LTRT-10632