We could be looking at a very interesting case coming down the pipes. Then again, the article points out that the last time this arose (that one involving Verizon) the company opted not to block the messages.
"T-Mobile told a federal judge Wednesday it may pick and choose which text messages to deliver on its network in a case weighing whether wireless carriers have the same “must carry” obligations as wire-line telephone providers.
The Bellevue, Washington-based wireless service is being sued by a texting service claiming T-Mobile stopped servicing its “short code” clients after it signed up a California medical marijuana dispensary. In a court filing, T-Mobile said it had the right to pre-approve EZ Texting’s clientele, which it said the New York-based texting service failed to submit for approval.
EZ Texting offers a short code service, which works like this: A church could send its schedule to a cell phone user who texted “CHURCH” to 313131. Mobile phone users only receive text messages from EZ Texting’s customers upon request. Each of its clients gets their own special word.
T-Mobile, the company wrote in a filing (.pdf) in New York federal court, “has discretion to require pre-approval for any short-code marketing campaigns run on its network, and to enforce its guidelines by terminating programs for which a content provider failed to obtain the necessary approval.”"