Yealink T74-W information
https://support.yealink.com/document-detail/7cd8bba573d24cf69bd16f7c7addbc4f
Very detailed overview of the phone and it's features. Content available under User Guide.
Yealink Quick Guide
A lot of quick codes
Yealink YouTube Video
https://www.youtube.com/watch?v=XeeMAq_51U8
8 minute video of a quick over view of buttons