libphonenumber\PhoneNumberUtil::maybeStripInternationalPrefixAndNormalize PHP Method

    public function maybeStripInternationalPrefixAndNormalize(&$number, $possibleIddPrefix)
    {
        if (mb_strlen($number) == 0) {
            return CountryCodeSource::FROM_DEFAULT_COUNTRY;
        }
        $matches = array();
        // Check to see if the number begins with one or more plus signs.
        $match = preg_match('/^' . static::$PLUS_CHARS_PATTERN . '/' . static::REGEX_FLAGS, $number, $matches, PREG_OFFSET_CAPTURE);
        if ($match > 0) {
            $number = mb_substr($number, $matches[0][1] + mb_strlen($matches[0][0]));
            // Can now normalize the rest of the number since we've consumed the "+" sign at the start.
            $number = static::normalize($number);
            return CountryCodeSource::FROM_NUMBER_WITH_PLUS_SIGN;
        }
        // Attempt to parse the first digits as an international prefix.
        $iddPattern = $possibleIddPrefix;
        $number = static::normalize($number);
        return $this->parsePrefixAsIdd($iddPattern, $number) ? CountryCodeSource::FROM_NUMBER_WITH_IDD : CountryCodeSource::FROM_DEFAULT_COUNTRY;
    }

 public function testMaybeStripInternationalPrefix()
 {
     $internationalPrefix = "00[39]";
     $numberToStrip = "0034567700-3898003";
     // Note the dash is removed as part of the normalization.
     $strippedNumber = "45677003898003";
     $this->assertEquals(CountryCodeSource::FROM_NUMBER_WITH_IDD, $this->phoneUtil->maybeStripInternationalPrefixAndNormalize($numberToStrip, $internationalPrefix));
     $this->assertEquals($strippedNumber, $numberToStrip, "The number supplied was not stripped of its international prefix.");
     // Now the number no longer starts with an IDD prefix, so it should now report
     // FROM_DEFAULT_COUNTRY.
     $this->assertEquals(CountryCodeSource::FROM_DEFAULT_COUNTRY, $this->phoneUtil->maybeStripInternationalPrefixAndNormalize($numberToStrip, $internationalPrefix));
     $numberToStrip = "00945677003898003";
     $this->assertEquals(CountryCodeSource::FROM_NUMBER_WITH_IDD, $this->phoneUtil->maybeStripInternationalPrefixAndNormalize($numberToStrip, $internationalPrefix));
     $this->assertEquals($strippedNumber, $numberToStrip, "The number supplied was not stripped of its international prefix.");
     // Test it works when the international prefix is broken up by spaces.
     $numberToStrip = "00 9 45677003898003";
     $this->assertEquals(CountryCodeSource::FROM_NUMBER_WITH_IDD, $this->phoneUtil->maybeStripInternationalPrefixAndNormalize($numberToStrip, $internationalPrefix));
     $this->assertEquals($strippedNumber, $numberToStrip, "The number supplied was not stripped of its international prefix.");
     // Now the number no longer starts with an IDD prefix, so it should now report
     // FROM_DEFAULT_COUNTRY.
     $this->assertEquals(CountryCodeSource::FROM_DEFAULT_COUNTRY, $this->phoneUtil->maybeStripInternationalPrefixAndNormalize($numberToStrip, $internationalPrefix));
     // Test the + symbol is also recognised and stripped.
     $numberToStrip = "+45677003898003";
     $strippedNumber = "45677003898003";
     $this->assertEquals(CountryCodeSource::FROM_NUMBER_WITH_PLUS_SIGN, $this->phoneUtil->maybeStripInternationalPrefixAndNormalize($numberToStrip, $internationalPrefix));
     $this->assertEquals($strippedNumber, $numberToStrip, "The number supplied was not stripped of the plus symbol.");
     // If the number afterwards is a zero, we should not strip this - no country calling code begins
     // with 0.
     $numberToStrip = "0090112-3123";
     $strippedNumber = "00901123123";
     $this->assertEquals(CountryCodeSource::FROM_DEFAULT_COUNTRY, $this->phoneUtil->maybeStripInternationalPrefixAndNormalize($numberToStrip, $internationalPrefix));
     $this->assertEquals($strippedNumber, $numberToStrip, "The number supplied had a 0 after the match so shouldn't be stripped.");
     // Here the 0 is separated by a space from the IDD.
     $numberToStrip = "009 0-112-3123";
     $this->assertEquals(CountryCodeSource::FROM_DEFAULT_COUNTRY, $this->phoneUtil->maybeStripInternationalPrefixAndNormalize($numberToStrip, $internationalPrefix));
 }