Auto Answer

[jolouis]

Just to be clear, you want to use a customized ring tone before the phone automatically answers? That's a pretty strange scenario and I would expect that Yealink does not support it...

(Usually the whole point of auto-answer is to get an open conversation as quickly as possible... the tone is just a quick note that something has happened. If you had a customized ring/sound, the user would have to wait for that to finish playing before the auto-answer actually kicked in, at which point it's more of a regular call then anything else).

If you're really heart set on this, one way of doing it would be to use ActionURL/ActionURI together with a script on your server. Something like:
1) Have you server set an Alert-Info: header to trigger your custom ring tone for this call
2) setup an ActionURL for "Incomming Call" to a script on your server
3) Set the script to sleep/wait however long your custom ring tone should be played (might take a bit of experimenting to get right but should be doable)
4) Have your script trigger the phone to answer by using ActionURI.

Not ideal but probably the best you're going to get as I doubt Yealink is going to write a new firmware for such an unusual request.