Contact::subscribe

public function subscribe($campaignId = null)
{
	if (!$this->getId())
	{
		return false;
	}

	$campaignId = $campaignId ?: Campaign::getDefaultId(SITE_ID);
	return MailingSubscriptionTable::addSubscription(array(
		'MAILING_ID' => $campaignId,
		'CONTACT_ID' => $this->getId(),
	));
}