on 11-11-2023 15:17
When I send a text the recipient receives the message but I get a failed to send error.
on 11-11-2023 15:26
on 11-11-2023 16:45
This happens often on iPhones because O2 don't support delivery reports so it confuses the system.
To get an accurate response, you need to start all your standard texts with *0# (will not be seen by recipient) and just ignore the iPhone reported status.