why am i not able to get deliver text message to a particular number?

[Android Central Question]

since 15 days i am noticing that while sending text message on a particular vodafone number, It is showing sent but not delivered. After 12 hours I receive an error sign on that particular message showing that Message is sent in message report, delivery time shows after 12 hrs. whatever it is. and status shows that UNSUCCESSFUL.
"Please help to get it clear" . Is the reason that person have blocked me?

 

[B. Diddy]

Welcome to Android Central! Try calling that person instead and seeing if you can reach them.