Cisco Systems SPA2102, SPA3102, WRP400 Register Retry is configured in the SIP tab. See ATA Voice

Introducing Cisco Small Business Analog Telephone Adapters	1
ATA Software Features

Feature	Description
Register Retry	The Register Retry Enhancements feature for SPA2102,
Enhancements	SPA3102, and PAP2T devices adds flexibility to the delay
	timers that are activated when the SIP REGISTER of a
	device fails. Once a SIP REGISTER failure response code
	is sent, a delay timer is selected depending on the type of
	registration failure response code. The delay timers can
	be one of the following:
	• Reg Retry Random Delay—Random delay range (in
	seconds) to add to the Register Retry Intvl parameter when
	retrying a SIP REGISTER after a failure. The default is 0,
	which disables this feature.
	• Reg Retry Long Random Delay—Random delay range (in
	seconds) to add to the Register Retry Long Intvl parameter
	when retrying a SIP REGISTER after a failure. The default is
	0, which disables this feature.
	• Reg Retry Intvl Cap—The maximum value to cap the
	exponential back-off retry delay. The exponential back-off
	retry delay starts with the setting found in the Register Retry
	Intvl parameter and doubles it on every REGISTER retry after
	a failure. In other words, the retry interval after a failure is
	always set to the seconds configured in the Register Retry
	Intvl parameter. If this feature is enabled, the Reg Retry
	Random Delay setting is added on top of the exponential
	back-off adjusted delay value. The default value is 0, which
	disables the exponential back-off feature.
	Register Retry is configured in the SIP tab. See “ATA Voice
	Field Reference,” on page121.

ATA Administration Guide 33