Hello Ahajee,
Welcome to the community!
Fido Roam is enabled by default on most current post-paid plans. If you did not wish to avail of the feature, you would have to opt-out of Fido Roam. In doing so, any usage would be on a pay-per-use basis. Those rates can be found here. Alternatively, if you did not wish to use any services, you would could request to have roaming blocked on your account. Though, a roaming block would also limit access to extended coverage in Canada (Fido-EXT). You would need to verify which option is applied to your account as some customers had assumed they requested a total roaming block only to find pay-per-use usage abroad (opt-out Fido Roam).
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. While receiving SMS would not incur the roaming charge, it's worth mentioning that the 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 also be noted that RCS messages are sent (and received) as data and not as text messages (SMS). Even if a received text message is SMS, if your device is configured to provide Delivery and/or Read receipts, those would be sent as SMS or data 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 unintended roaming usage. You could then manually enable Wifi when required.
For completeness sake, 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 far as I am aware, disabling roaming does not prevent Wifi-calling usage abroad and therefore could still incur roaming charges.
You should note the forums are community-driven and not intended as a venue for customer services. If you wished to discuss your matter and/or opt-out of Fido Roam or block roaming, you would need to contact customer service
Hope this helps š
Cheers
