The other day a business person tried to become a registered member on my website who is based in the US. He entered the phone number but was thrown out with a message saying it's not numeric.
Now, I know why it through the message, because he had entered the number with the minus sign inbetween the numbers. Do the US always place the minus sign inbetween the phone numbers? Have you had problems due to this?
In the mean time I'll place a message requesting not to place anything else except for numbers.