Transfer to VM button not working

General Help
1

I need to setup a blind transfer to voicemail button in endpoint manger. If i hit transfer, then hit * extension it works. I have tried setting up a prefix with no luck. What is the proper way of doing this?

2

what model of phone you are using?. that look more like a script key

3

Yealink T29G

4

please refer to that document from Yealink:

http://download.support.yealink.com/download?path=upload%2Fattachment%2F2016-12-1%2F3%2Feb171d62-d60e-4c1b-b7aa-7a1b8c37d716%2FUsing%20Enhanced%20DSS%20Keys%20on%20Yealink%20IP%20Phones_V81_20.pdf