I just discovered that the nine number keypad on your keyboard is totally different from the number keypad on any phone or cell phone. I just about had a brain aneurysm trying to convert "vanity phone numbers" like 1-800-MC-ASSIST into real phone numbers today at work. Instead of starting with 1 at the top left corner, your keyboard starts with 7 and it doesn't list letter options along with the numbers.
It's amazing how your brain just subconsciously knows that the phone and keyboard are set up differently. It never tripped me up until today. I wonder if Skype and Vonage customers have a hard time with this too.