Text - user is offline

[Scottl]

I'm new to O2. Since I changed, my wife can no longer text me without getting a text fail message. It says the text will be received when the user (me) is back online. If she selects the error there is the option to resend by sms/mms. Which works...we have tried deleting text app cache, deleting all messages and removing each others contacts. All to no avail. The problem persists. It doesn't effect any of her other contacts, just me. And I do not have any problems texting her...?

[Cleoriff]

@Scottl 

Check out this guide Guide: Text Message Tips (not sent or received) 

[MI5]

@Scottl 

Check the advanced messaging option found in message settings, you may have got "chat" toggled on and you will need to turn the setting off.