Telephone number validation and formatting

I’m working to build a telephone number validation and formatting
method.
I’m attaching an address_helper I use for this.
I’d like to get comments on it.
The method is based on extending the country model by adding 4 integer
attributes: tel_min, tel_max, tel_area_min and tel_area_max which are
the minimum and maximum number of digits of the telephone number in each
country and the minimum and maximum number of digits in the telephone
area code.
Please comment.
Thanks,
Raffi