I am a T-mobile user and got two "Dear Homeowner" mortgage spam text messages in the span of 7 days. The messages are identical to those described above but from a different phone number with same area code: 323-236-7284.
Read this article about Facebook quizzes and privacy:
http://www.npr.org/templates/story/story.php?storyId=114187478&ft=1&f=1001
If your phone number is on your Facebook profile and you take quizzes or use Facebook apps, it's possible a malicious developer pulled your phone number and sold it to this spammer. I believe this is how they got my phone number and sent the message.
I received an unsolicited text message from this number about lowering my mortgage payments. I called the number back from a private line and the voicemail said "The voice mailbox you are calling for 'Stupid Telemarketer' is full. Please call back later."
At least they're honest about their abilities and professions...