You program a feature button on an Edge IP 9800 Series phone as an external SIP line that registers to the alternate call server, instead of to the Wave that the phone is primarily registered to.
Each ESL button is associated with an extension on the alternate call server that is set up specifically for ESL. In a typical scenario, for each ESL button programmed for users on the Wave primary call server, there needs to be a corresponding extension defined on the alternate call server to support ESL.
If the Wave primary call server is not available and a user’s phone is configured with an ESL button, the alternate call server can then be used to make and receive calls. The Primary button on the phone blinks to indicate a non-operational state, but the display screen on the phone still identifies the ESL button.
- To make an outbound call via the alternate call server, the user selects the ESL button. At dial tone, the user can then call any extension or external number allowed for the associated extension on the alternate call server.
- An inbound call from the alternate call server rings the user’s phone and can be answered by selecting the ESL button.
When the Wave primary call server becomes available again, any current calls using ESL will continue without interruption.