Why is my Samsung GT-S7500 telling me it has been blocked due to suspicious activity?

[AC Question]

my samsung GT-S7500 is telling me it has been blocked due to suspicious activity.

samsung GT-S7500 Blocked due suspicious activity. apps work fine and internet is working. but it wont let me send or receive TXT or phone calls.

 

[B. Diddy]

Re: my samsung GT-S7500 is telling me it has been blocked due to suspicious activity.

Welcome to Android Central! Might be something to do with Knox, Samsung's security app. Have you spoken to your carrier about this?