Mobile phone reception.

aqua111

My Sister and I use very basic phones for Pay As You Go.
We txt each other daily but suddenly, although my phone says delivered and the copy is in my Sent Box, my Sister is not receiving the messages.
If I call her there is no problem.
She can txt me but does not receive my reply.
We have no problem with any of our other numbers.
My Sister has checked her Blocked Senders but it is empty.
I am with Orange and she is with Talk Talk.
Can anyone help?

bingo_bango

IIRC the older phones had a setting for the SMS 'center' number. I vaguely remember having a similar problem some years ago on an old Nokia which meant I had to add the SMS number back into settings every month or so.

Three would send a message with the details when you called to ask them about it. Perhaps worth both of you checking this with your respective operators?