Have any customers ever complained about not being able to use IVR's (e.g banking) and not being able to enter their account numbers ??

I just got off the phone with one of my customers who was trying to buy a Treasury Note....she said that our IVR was not recognizing her account number....when I heard her input her account number, the DTMF tones were very long....therefore, not recognizing her account number.

I am thinking that the problem is with the touch screen, not being able to control the amount of pressure it would take to depress a key on the keypad.

Is this an issue with I-Phones or touch screens in general ??