I have a Lumia 925 running on Tmobile. Every so often I come across a sentence or phrase that is blocked or somehow prevented from being sent. The most recently rejected message is,"Seven hour day?" "Are you receiving this?" is another. I get no error code, just the message, "The message you sent to (phone number) wasn't delivered. Make sure the address is correct, and then try sending the message again." I have installed no third-party applications. I have deleted all text messages and have rebooted the device several times. My daughter has the same phone and service and when I had her text me one of the phrases in question, I never received it. Has anyone else experienced this, or know why this occurs and how to correct this?