default = 'Bob';
$hsmParamsWhen = new MessageBirdObjectsConversationHSMParams();
$hsmParamsWhen->default = 'Tommorrow!';
$hsmLanguage = new MessageBirdObjectsConversationHSMLanguage();
$hsmLanguage->policy = MessageBirdObjectsConversationHSMLanguage::DETERMINISTIC_POLICY;
//$hsmLanguage->policy = MessageBirdObjectsConversationHSMLanguage::FALLBACK_POLICY;
$hsmLanguage->code = 'YOUR LANGUAGE CODE';
$hsm->templateName = 'support';
$hsm->namespace = '6b75a6a3_b82c_4c62_a8cd_f1f3d3527161';
$hsm->params = array($hsmParamsName, $hsmParamsWhen);
$hsm->language = $hsmLanguage;
$content->hsm = $hsm;
$message = new MessageBirdObjectsConversationMessage();
$message->channelId = 'b58e902517124d5e948e278ebe40aa6d';
$message->content = $content;
$message->to = '5215525269173';
$message->type = 'hsm';
try {
$conversation = $messageBird->conversations->start($message);
var_dump($conversation);
} catch (Exception $e) {
echo sprintf("%s: %s", get_class($e), $e->getMessage());
}