$re = '/(?:https?:\/\/)?wa\.me\/\d{3,15}/m';
$str = 'https://wa.me/29483294837?text=
text=I\'m%20interested%20in%20your%20car%20for%20sale
https://wa.me/29483294837?text=I\'m%20interested%20in%20your%20car%20for%20salehttps://wa.me/29483294837?text=I\'m%20interested%20in%20your%20car%20for%20sale
https://wa.me/29483294837?text=I\'m%20interested%20in%20your%20car%20for%20sale
https://wa.me/2948d3294837?text=I\'m%20interested%20in%20your%20car%20for%20salehttps://wa.me/s29483294837?text=I\'m%20interested%20in%20your%20car%20for%20sale
https://wa.me/29483294837?text=I\'m%20interested%20in%20your%20car%20for%20sale
https://wa.me/29483294837text=I\'m%20interested%20in%20your%20car%20for%20salehttps://wa.me/29483294837?text=I\'m%20interested%20in%20your%20car%20for%20sale
https://wa.me/226495150463435?text=I\'m%20interested%20in%20your%20car%20for%20sale';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php