Not able to sendKeys to Number keypad in iOS 7

So I have a field for inputting mobile number in my application. When I tap on it, it opens a number-only keypad. Here’s the screenshot for the same :

The problem is that when I do a send Keys on this field ( it’s a textField) it does not type anything. Just gives an error. Is there any other way to automate a numeric keypad?

I am using appium 1.2 with Java Client. Please let me know. Stuck here for quite some time now.

try driver.sendKeyEvent(int)

So should I call sendKeyEvent(int) for every number that I want to press? Or can I send the whole number to the method?

One by one. Refer the below link for keycode