Why some of my contacts did not received my Text Message?

Some people need to enable their cell phone's messaging by contacting their mobile providers. There are people who use pre-paid phones, that might not have a high enough balance to cover the incoming message. Some recipients need to subscribe to receive a higher number of Text Messages. Sometimes the recipient is out-of-range and cannot receive the message. Sometimes the mobile number of the recipient is wrong and will not get delivered properly.