Cisco 521SG Administration Guide - Page 238

Cisco SPA IP Phone Field Reference SIP Tab A Parameter Reg Retry Long Random Delay Reg Retry Intvl Cap Sub Min Expires Sub Max Expires Sub Retry Intvl Description Random delay range (in seconds) to add to when retrying REGISTER after a failure. This feature was added in Release 5.1. Defaults to blank, which disables this feature. The maximum value to cap the exponential backoff retry delay (which starts at and doubles on every REGISTER retry after a failure). In other words, the retry interval is always at seconds after a failure. If this feature is enabled, is added on top of the exponential back-off adjusted delay value. This feature was added in Release 5.1. Defaults to blank, which disables the exponential back-off feature. This value sets the lower limit of the REGISTER expires value returned from the Proxy server. This value sets the upper limit of the REGISTER min-expires value returned from the Proxy server in the Min-Expires header. Defaults to 7200. This value (in seconds) determines the retry interval when the last Subscribe request fails. Defaults to 10. NOTE Cisco IP phones can use a RETRY-AFTER value when received from a SIP proxy server that is too busy to process a request (503 Service Unavailable message). If the response message includes a RETRY-AFTER header, the phone waits for the specified length of time before retrying to REGISTER again. If a RETRY-AFTER header is not present, the phone waits for the value specified in the Reg Retry Interval or the Reg Retry Long Interval parameter. Cisco Small Business SPA300 Series, SPA500 Series, and WIP310 IP Phone Administration Guide 237