Allow only Numeric values to enter in Text-field

I am facing issue to allow only Numeric values in Text-field. I have set

txtMobile.keyboardType = Ti.UI.KEYBOARD_NUMBER_PAD
 
txtMobile.keyboardType =Ti.UI.KEYBOARD_PHONE_PAD

Following are the details. Titanium sdk : 3.4.1 Build Platform : Android

Thanks in Adv.