Hi, Joe--sorry for the late reply, we somehow missed this message.
CTA's text messaging service for CTA Bus Tracker and CTA Train Tracker are services that we've built and which are accessible through 41411, which is a shared text messaging shortcode provided through a company called Textmarks.
There are no APIs related to Bus Tracker or Train Tracker's text messaging services, though the underlying data available through these services is available through our APIs (estimated arrival times, service alerts, etc.).
Thanks for your interest in our open data.
-TC