/*
 * Utility functions for NANP number validation.
 */

is_nanp_valid_prefix(s)
	char *s;
{
	/* validate NPA part */
	if (s[0] < '2')
		return(0);
	if (s[1] == '1' && s[2] == '1')
		return(0);
	/* validate exchange part */
	if (s[3] < '2')
		return(0);
	if (s[4] == '1' && s[5] == '1')
		return(0);
	/* all checks passed */
	return(1);
}