libphonenumber\PhoneNumberUtil::format PHP Method

    public function format(PhoneNumber $number, $numberFormat)
    {
        if ($number->getNationalNumber() == 0 && $number->hasRawInput()) {
            // Unparseable numbers that kept their raw input just use that.
            // This is the only case where a number can be formatted as E164 without a
            // leading '+' symbol (but the original number wasn't parseable anyway).
            // TODO: Consider removing the 'if' above so that unparseable
            // strings without raw input format to the empty string instead of "+00"
            $rawInput = $number->getRawInput();
            if (mb_strlen($rawInput) > 0) {
                return $rawInput;
            }
        }
        $metadata = null;
        $formattedNumber = "";
        $countryCallingCode = $number->getCountryCode();
        $nationalSignificantNumber = $this->getNationalSignificantNumber($number);
        if ($numberFormat == PhoneNumberFormat::E164) {
            // Early exit for E164 case (even if the country calling code is invalid) since no formatting
            // of the national number needs to be applied. Extensions are not formatted.
            $formattedNumber .= $nationalSignificantNumber;
            $this->prefixNumberWithCountryCallingCode($countryCallingCode, PhoneNumberFormat::E164, $formattedNumber);
        } elseif (!$this->hasValidCountryCallingCode($countryCallingCode)) {
            $formattedNumber .= $nationalSignificantNumber;
        } else {
            // Note getRegionCodeForCountryCode() is used because formatting information for regions which
            // share a country calling code is contained by only one region for performance reasons. For
            // example, for NANPA regions it will be contained in the metadata for US.
            $regionCode = $this->getRegionCodeForCountryCode($countryCallingCode);
            // Metadata cannot be null because the country calling code is valid (which means that the
            // region code cannot be ZZ and must be one of our supported region codes).
            $metadata = $this->getMetadataForRegionOrCallingCode($countryCallingCode, $regionCode);
            $formattedNumber .= $this->formatNsn($nationalSignificantNumber, $metadata, $numberFormat);
            $this->prefixNumberWithCountryCallingCode($countryCallingCode, $numberFormat, $formattedNumber);
        }
        $this->maybeAppendFormattedExtension($number, $metadata, $numberFormat, $formattedNumber);
        return $formattedNumber;
    }

 /**
  * @return string
  */
 public function __toString()
 {
     $phoneNumber = $this->getPhoneNumber();
     $format = $this->getFormat();
     if (!$this->getPhoneNumber() instanceof PhoneNumber) {
         $phoneNumber = $this->parsePhoneNumber();
     }
     return $this->libPhoneNumber->format($phoneNumber, $format);
 }