SMS breaks when upgrading to version 2 of extension & 4.6.2 of CIVICRM
I use Twilio, but had this problem too. I found what i believe to be a bug in Civi's mailing code (which also handles sms'es).
In the function create in CRM/Mailing/BAO/Mailing.php on line 1755, getRecipients are called without the last argument $mode, and getRecipients are executed as if it's an email and not an SMS. I added a check to see if it's and sms, and added the extra argument, and it worked for me:

  // Populate the recipients.
  if (empty($params['_skip_evil_bao_auto_recipients_'])) {
    // check if it's an sms
    $mode = $mailing-&gt;sms_provider_id ? 'sms' : NULL;
    self::getRecipients($job-&gt;id, $mailing-&gt;id, NULL, NULL, TRUE, $mailing-&gt;dedupe_email, $mode);
  }


Read more at the issue I filed here.