Formats a phone number into a chosen representation and reports whether the number is valid.
tel: URI (RFC3966).Pass an international number, or set region for national-format input. format is one of e164 (default), national, international, rfc3966. Computed locally.
Output format. Defaults to e164.
The phone number. Include + and country code, or set 'region'.
Optional default region (2-letter ISO code) for national-format numbers.