Refresher

The initial UAC, the side that sends the INVITE, can set itself to be the refresher (uac) or the Oracle Communications Session Border Controller as the refresher (uas). Whoever is the refresher is indicated in the 200 OK. If the UAC does not specify any refresher, the Oracle Communications Session Border Controller uses it’s response-refresher value in the 200 OK. If that value is set to uas, the Oracle Communications Session Border Controller creates and sends a re-INVITE toward the UAC with previously negotiated session expiration values.

Once the Oracle Communications Session Border Controller becomes the refresher, it does not relinquish that role. Then, when the Oracle Communications Session Border Controller sends refresh requests, it does not change any parameters (refresher role & timers) from the initial request negotiation.