@tarbender - seeing that your post got hi-jacked a bit, let me try to help:
1. the 3CX Phone for Windows V12 operates in eiter CTI mode (connects to a supported Telefone and dials out via that phone), or as standalone SIP Phone on your Windows PC/Notebook.
2. In CTI Mode, the client gives access to certain functions on the 3CX PhoneSystem like presence, call history, conference scheduler etc, and also a dial pad plus hot-key dialing (like copy / paste + deisgnatet hotkey). It is important that the desk phone uses the firmware recommended by 3CX, else the CTI part does not work. To update the firmware, in the management console go to your telephones overwiew, select your T46G, then in the top right corner is a small arrow icon, drop down menu, Firmware Update. This automates the process and installes the correct firmware on your phone.
3. To set the default mode of the 3CX Phone for Windows V12, in the management console edit the extension, tab 3CX Phone, chose the default type and start up screen, for example SIP Phone if you dont want CTI mode, or the other way round.
Now if I recall correctly, the newer Yealink Phones like the T46G are not yet fully integrated with the 3CX Phone Windows V12, in other words it uses the "Make Call" feature rather than automated CTI - at least that is what it does here on my side. I can dial a number from the 3CX Phone, and on the Yealink T46G get the option to make the call. Incoming calls are shown in the 3CX Phone client, but I can't answer it via the client, have to answer on the phone itself. On the older Yealink models like T38G and T28, as well as certain snom models, the CTI works with the correct firmware installed on the telephone.
Hope I was able to shed some light there for you..