What do you do when one of your potential subscribers attempts to opt-in to your list and they receive one of the following messages:
Short code may have expired or short code texting may be blocked on your account. Msg 1051.
Service Access Denied
Problem: This means the mobile phone in question does not accept short code messages.
Solution: All the mobile phone subscriber has to do in order to turn on short code messaging is call their mobile provider. The majority of the time for this case, it's because a past mobile phone subscriber had short code messaging turned off.