keypad fquickness

It sounds like you're using standard Voiceover typing which is very, very slow. If you go to your voiceover settings you can change your input method to either touch typing (where it will say the letter or number when your finger is on it, but type it as soon as you lift your finger) or direct touch typing (which makes the keyboard behave as it would if voiceover was off.)

I don't know if you would be willing to buy a bluetooth keyboard, but it is extremely helpful. I have figured out that my keyboard can be used to dial phone numbers and also for touch tones while on a call. I find it almost impossible to hear VoiceOver well enough when on a call to find the number I want. If you do invest in a bluetooth keyboard you will always be able to use it for what ever devices you have in the future as well as for your current iPhone. And of course it is useful for more than phone calls. I certainly wouldn't be typing this message on my phone without the keyboard. I can type on the screen fine, but it's always a little slow and painful even after you switch to VoiceOver touch typing mode.

Use a keyboard. I have 2 Rivo2 keyboards they work well.

I didn't realize they added the keyboard capability to phone dialing. Must have been recently. I can throw the ugly guide I made for the keypad away.

Other than the Rivo, which is a bit pricey, are there any numeric or numpad only Bluetooth keypads that would facilitate entering numbers while on a call?