Received text from Openreach to confirm engineer visit but all replies return not sent.
i am using Samsung A14 on Tesco Mobile. All other texts are working.
Is your phone set not to allow you to send text which maybe are not free hence why you cannot send to openrech
I think that it is all pretty mysterious.
A few days ago I had exactly the same experience as you. Then yesterday I had a follow-up text from the same Openreach number and my reply went through perfectly although I had certainly not changed any settings on my phone.
By coincidence, however, mine is a Samsung A15 on Tesco mobile. Of course, Tesco Mobile runs on the O2 network, so perhaps the problem was there.