Voicemail access number is going to be *97 or some other *#X. type pattern. It is not going to be letters. It would be nice if one didn’t have to change input types to get to a selection that includes the * without having to go through numerous button presses on the phone. I’m sure this is useful in other fields as well.
So we recommend a “nothing” class of input that is simply the thing that is printed on the button. Meaning: 123456789*0# and nothing else. This would make it easier for users to configure the phone from the phone.