jbush82 what app version are you using, and on what Windows version?
We have only seen the on screen keyboard issue on Windows RS5 / 1809, which is why we have not supported it so far.
We do support DTMF dialing on systems set as Teams default since our last (prior to this) app version. However, DTMF is ONLY supported in calls and NOT Teams Meetings. So if you start a Teams Meeting and then try to do DTMF we won't show the dialpad. The reason is that we do not support DTMF tones in meetings at all, so we hide the dialpad to avoid confusion. We don't support DTMF in meetings for privacy,since everyone on the meeting could hear (and record) the dial tones; someone could (as an extreme case) record your private conferencing PIN, or other private DTMF code.
We are looking again at how we could support DTMF in meetings, with appropriate privacy, but its a complex problem and we don't have a timeline right now.