A dropped SMS request can be due to several reasons. Click on the tooltip next to the status to see a possible reason why the request was not able to send. Most likely it’s due to:   The phone number is a landline and is unable to receive text messages. The number has blocked receiving messages from unknown numbers. The phone associated with this number is turned off or unavailable. The number you’re trying to send to may no longer exist. And occasionally an SMS message will not be delivered due to being flagged by the mobile carrier or an unknown error. This can happen because of spam filtering by the service provider. In this case, you can wait a moment and try to send the message again.