on 25-09-2014 20:27
O2 don't support delivery reports even if you tick the option. I believe it has been known to work on one model of phone and O2 don't charge.
To get a delivery report start each message with *0#
on 25-09-2014 20:29
OnePlus 6 (O2 & Sfr), Z3 Tablet (Three UK), iPhone 8+ (EE)