Really really bad for apple IOS

I have used Google voice plenty of times on my old Android device and it worked seamlessly as if it were a regular phone call. However, upon switching to an iPhone and trying to use Google Voice, a lot of the features on the app really buggy. One of the main things is when you make a call, and youre required to use the keypad to make an option selection, the keypad wont appear, and when it does, the entire screen freezes and you cant do anything but hang up and try again and again. Quite frustrating

itsBing about Google Voice, v2.5