Hello Graham8,
Welcome to the community!
Firstly, you should note that this forum is community-driven and not intended as a venue for customer services.
The Fido Roam charges will only incur if your phone uses services -- make or receive a call, send a text message or use data abroad. The mobile providers only know usage. If there is no usage abroad, there will be no roaming charges.
If you did not wish to use Fido Roam, you would need to opt-out of the feature. In doing so, any usage would be on a pay-per-use basis. You can view those rates in the link provided above. If you wished to opt-out of Fido Roam, you would need to contact customer service. In addition, they can also be contacted via Live Chat, Facebook, or Twitter. Those methods can be accessed via the contact page posted above.
It should be mentioned that while receiving SMS would not incur the roaming charge, any data contained within MMS (incoming or outgoing) would be considered roaming data and charged accordingly. You should note that MMS are not solely restricted to pictures or video messages. Messages with subject headers or group messages etc are also considered MMS. It should further be noted that iMessages and RCS messages are sent (and received) as data and not as text messages (SMS). Even if the text message received is SMS, if your device is configured to provide Delivery and/or Read receipts, those would be sent as SMS and considered roaming usage.
In order to prevent unintended roaming charges, it is generally recommended to disable data and roaming data. However, you should note that disabling those settings does not prevent roaming for voice and messaging. In addition, some manufacturers might allow some data usage to occur despite those settings (see here). That's why it is also generally recommended to enable Airplane and/or Flight modes in order to prevent unplanned roaming usage. You could then manually enable Wifi when required. Alternatively, people have also removed their Fido SIMs card entirely.
As already mentioned, making or receiving calls abroad will likely incur the Fido Roam charges. While letting calls go to voicemail does not incur any charges, you should note that checking your voicemail would incur charges as it involves calling the voicemail service.
As well, it should be noted that while using Wifi for regular internet access will not incur Fido Roam charges, there seems to be some misunderstanding regarding Wifi-calling. I'm not sure how people have gotten the impression that Wifi-calling does not use the networks. However, that is not true. While the calls and messages do not transmit via cellular towers, they still use the networks via the internet gateway (see image here). The cellular towers and Wifi are merely alternate means of accessing the networks. Calls and messages would not be able to complete or get sent/received without the networks. As such, using Wifi-calling is technically using Fido services. However, they have allowed certain usage to be free from additional charges. All the messages and calls you receive (from anywhere in the world) will be taken from your plan's voice minutes and messaging limits. As well, all Wifi-calling messages and calls you make to a Canadian phone number while abroad won't incur long-distance or roaming charges (see link above).
As mentioned, the mobile providers only know usage. If a device is using services when its settings are set not to use them, that's an issue with the device. The mobile providers have no access to a device's settings to know what settings are enabled/disabled. In order to not incur roaming charges, you would need to ensure your device does not allow any usage of services by whatever means necessary -- by enabling and/or disabling device settings or removal of Fido SIM card.
Hope this helps 😀
Cheers
