Keypad dialtones don't work during call

[widdlewade]

I've been travelling a lot lately, and find myself some times making a call only to realize that the keypad dialtones don't work. As a result accessing can be hard, since I can't press the numbers needed to acess the functions needed. Occasionally, a soft reset will fix it, but not all the time.
The phone is up to date with all updates. Thanks for any help.