I presume that you can send text messages without a problem?
If you were using an advanced messaging platform such as iMessage (Apple), RCS (Android), or Verizon Messenger+ (Verizon), and are not logged into the same advanced messaging platform on XM, then you need to login to the same platform. If you now have a different device that cannot use your previous platform, then you need to remove yourself from the old platform by logging into the old platform from a browser or another device.
To deregister from iMessage: https://selfsolve.apple.com/deregister-imessage/
To deregister from RCS: https://messages.google.com/disable-chat
Your contacts that were on the same platform as you were on will not be able to send you texts until you either remove yourself from that platform or login to that platform from your new device.