7 and 10 digit US phone number validation

Validate Phone Number

function validatePhoneNumber(phonenumber) {
	var pattern = /^(?:(?:\(\s*([2-9]1[02-9]|[2-9][02-8]1|[2-9][02-8][02-9])\s*\)|([2-9]1[02-9]|[2-9][02-8]1|[2-9][02-8][02-9]))\s*(?:[.-]\s*)?)?([2-9]1[02-9]|[2-9][02-9]1|[2-9][02-9]{2})\s*(?:[.-]\s*)?([0-9]{4})(?:\s*(?:\s+|#|x\.?|ext\.?|extension)\s*(\d+))?$/i;
	var matches = [];
	var validnumber = [];
	validnumber.unformatted = '';

	if (phonenumber.length > 0) {
		if (pattern.test(phonenumber)) {
			matches = phonenumber.match(pattern);
			// split phone number input into phone number format array
			for (var i = matches.length - 1; i >= 0; i--) {
				if (matches[i] !== undefined && i !== 0) {
					switch (i) {
						case 5:
						validnumber.extension = matches[i];
						break;
						case 4:
						validnumber.suffix = matches[i];
						break;
						case 3:
						validnumber.prefix = matches[i];
						break;
						case 2:
						validnumber.areacode = matches[i];
						break;
						case 1:
						validnumber.areacode = matches[i];
					}
				}
			}
			if (validnumber.areacode) {
				validnumber.unformatted = validnumber.areacode;
			}
			if (validnumber.prefix) {
				validnumber.unformatted += validnumber.prefix;
			}
			if (validnumber.suffix) {
				validnumber.unformatted += validnumber.suffix;
			}
			if (validnumber.extension) {
				validnumber.unformatted += validnumber.extension;
			}
			return validnumber;
		} else {
			return false; // invalid phone number
		}
	} else {
		return false; // nothing passed
	}
}