What does service not activated network mean when sending test to multiple recipients?

[AC Question]

Sent a text to 4 recipients on my Motorola Android and received the above message when I hit the send button. This is a new problem. Have texted many times with no problems.

 

[B. Diddy]

Welcome to Android Central! Which Motorola phone, and which carrier? Is your mobile data turned on? A group text is sent as an MMS message, which requires mobile data to be turned on.