Twilio and CiviCRM integration allows delivering single and mass short message service (SMS) messages through its Twilio Gateway to mobile phone users.
Installation instructions: http://wiki.civicrm.org/confluence/display/CRMDOC/Setting+up+a+SMS+Provider+for+CiviSMS or https://docs.civicrm.org/user/en/stable/sms-text-messaging/set-up/#configuring-a-twilio-sms-gateway