Welcome to the community!
Had you previously been using Fido services with a different phone? If so, is your new phone using your old SIM or your new SIM? If it's your new SIM, you would need to activate the SIM for use in that phone. You should be able to update your SIM via My Account --> Usage & Services --> Mobile (or select phone number) --> Update SIM card (under Quick Actions, near bottom of page). You'll be required to enter the old SIM details as well as the new SIM details.
If your new phone uses the same SIM size as your old phone, you should be able to use your old SIM in your new phone without the need to update SIMs.
Hope this helps 😀