Text messages still going to old sim card

[Jamie1976uk]

Hi.  I recently joined o2 from vodafone and kept my old number.  Some of my text messages , but not all of them,  seem to be getting delivered to my old phone though instead of my new one.  It's been a week since my number  was moved. Its not that they're get delivered to both phones , some just go to my old one and not my new one.  Anyone know how to stop this from happening?  Thanks

[jonsie]

In the phone go to settings/phone/my number

Edit, save and reboot the phone

[Jamie1976uk]

Theres nowhere in the settings with the heading 'phone'? There's "about my phone" and it says "unknown" against 'my number'. But it doesn't let me edit it

[MI5 · Accepted solution]

@Jamie1976uk 

You need to go into message settings and look for RCS under advanced settings.

You may need to deregister your old phone in the same way too.