Три способа авторизации в Битрикс: по телефону, email и логину

AddEventHandler('main', 'OnBeforeUserLogin', function(&$params) {
    $input = $params['LOGIN'];
    
    if (preg_match('/^[\d\+\-\(\)\s]+$/', $input)) {
        $user = CUser::GetList('id', 'asc', ['PERSONAL_PHONE' => NormalizePhone($input)])->Fetch();
        if ($user) $params['LOGIN'] = $user['LOGIN'];
    } 
    elseif (filter_var($input, FILTER_VALIDATE_EMAIL)) {
        $user = CUser::GetList('id', 'asc', ['EMAIL' => $input])->Fetch();
        if ($user) $params['LOGIN'] = $user['LOGIN'];
    }
});

function NormalizePhone($phone) {
    return preg_replace('/[^\d]/', '', $phone);
}