My wireless home phone can't send the pressed number if I am trying to join a conference or responding to automated menu. This used to work but it seems to have stopped working last month or so. I have already tried 3 different phones with this.
Could you perhaps provide us with some context and more details on the situation? Are you perhaps trying to use your phone's menu to initiate a conference call?
Joining one would only require you to answer the call you've received (someone else initiated the conference call). Alternatively, you can also join a conference call using a dedicated number for it, if you're the one calling.
That said, let us know us so we can narrow it down together