I set up voicemail and my number has changed on outgoing texts.

iPhone or Android?

Android.  Sorry - should have said.

You may have already tried this, but it’s worth checking. Do the below steps work in updating the number in the chat settings?

1) Open Messages, go to Settings (top right, Message Settings), open "Chat Features" or "RCS Chats", verify if this is the correct number or not.

2) If it shows the incorrect one, then head to: https://messages.google.com/disable-chat and you should be able to unregister the number. Once done, turn off the Chat Features/RCS and the phone. Wait a few minutes and turn the device back on and re-enable Chat Features/RCS it should let you re-register/update to the correct number. Alternatively, you can turn Chat Features/RCS off and test SMS after this

If this doesn’t work, it will be worth trying a replacement SIM. This would be a blank SIM card later activated with your number, so it won’t have an association with a temporary number. You would be able to collect one at a local Currys store. Alternatively you can order one to be sent out. 

Hi again!  Thanks so much for taking the time to reply.  I have tried what you suggest and the incorrect number is showing.  When I head to your suggested URL, there is no option to up-date to unregister the number.  Also attempted to  change in RCS Chat, but no change.  A replacement blank SIM sounds the best solution.  Could you tell me how I order one?  Many thanks!

Thanks! You are a life-saver!

Hey there ​@jj01, we’re glad to see that ​@MZone was able to help, thank you!

Please let us know if you have any further questions.

Thanks,

Tyler