Note that only phone numbers in the United States of America and Canada are supported at this time.
If you are unable to receive text messages, it's possible that your phone or carrier is blocking our text messages. Our messages are sent from a variety of numbers, so there is not a specific number we can tell you to unblock. You can do a web search to find how to block and unblock SMS/text message senders on your particular phone or with your particular mobile carrier.
If you are still having problems, submit a request with details (the target phone number, your mobile provider, and an approximate date, time, and time zone at which you feel a message should have been sent) so that we can investigate further.