message send failure after update 6s
After updating my 6s, my i phone constantly has problems sending a message.
It is often returned with 'MESSAGE SEND FAILURE"
Also, sometimes the name of the person comes up. Other times it is the phone number written weirdly.
For example, 51 62 879 123.
My friend looked at settings today and something came up saying I need to activate my imessage.
She was unable to solve the problem.
Help
Thank you
iPhone 6s, iOS 13