Hello @Schofield1221,
Welcome to the community!
You can either take out the SIM card when you are leaving or you can contact customer service and ask to have a roam block applied to your line this way the phone will not connect to any other carrier but Fido, I find this is the best way I've had this on my lines for years and never had any problems.
Hello, again @Schofield1221 the block would only be for Fido services and will not affect any other service provider SIM/eSIM you use.
