public function getNumericCountry()
    {
        $country = $this->getCountry();

        if ( !is_null($country) && !is_numeric($country) )
        {
            $iso3166 = new ISO3166();

            if ( strlen($country) == 2 )
            {
                $country = $iso3166->getByAlpha2($country)['numeric'];
            }
            elseif ( strlen($country) == 3 )
            {
                $country = $iso3166->getByAlpha3($country)['numeric'];
            }
            else
            {
                throw new InvalidRequestException("The country parameter must be ISO 3166-1 numeric, aplha2 or alpha3.");
            }
        }

        return $country;
    }