Unable to upgrade Yealink T46S

I have been having a lot of issues upgrading Yealink phones. Specifically it is the upgrade path that 3CX wants you to use. I had one system with v15 and another system with v15.5. Now they are both on v16. However, v16 has been out for many months and in that time there has been some more firmware updates.

I like updates and am very adamant about keeping everything up to date. The problem is Yealink and 3CX only lists the latest firmware. Now, since there was a middle firmware that was released between v15.5 and v16 I need to upgrade to that one first before I can go to the latest version.

In case anyone needs it here is the firmware that I couldn’t find a link to: This firmware is needed in order to upgrade a T46S from 66.83.x to 66.85.x.