Recommendation Attribute for Phone Number ?

Hai All,

I make one attribute, is function to the attribute is note for phone number or mobile phone customer.

Attribute have Date Type : String, StringSubDateType : PhoneNumber, and Max.Length : 12.

But, the problem is, where customer complete data my customer want just NUMERIC NUMBER if customer complete data and don't want Alphabet.

Any idea for this problem ??

Trims.

Putri Cantik