Hello SVM1,
Welcome to the community!
Firstly, what plan-type do you have? You should note that some plans (ie Basic plans) do not allow for roaming. If you have a plan which does includes roaming, it should be mentioned that Fido Roam is already enabled. Customers not wishing to use the feature would need to opt-out of Fido Roam. In doing so, usage would be on a pay-per-use basis. You can view those rates here.
The Fido Roam charges will incur if your phone uses services -- make or receive a call, send a text message or use data abroad. So yes, you should be able to receive calls while in Dubai if you have a Data, Talk & Text or Talk & Text plan.
I understand you do not intend on using data. You should note that while receiving SMS would not incur the roaming charge, the data contained within MMS (incoming or outgoing) would be considered roaming data and charged accordingly. You should also note that MMS are not solely restricted to pictures or video messages. Messages with subject headers or group messages etc are also considered MMS. Disabling MMS should prevent that data transfer. Though, it should further be noted that iMessages and RCS messages are sent (and received) as data and not as text messages (SMS).
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. However, those modes would also prevent the phone from receiving calls.
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).
You might consider verifying your phone is compatible with the local bands/frequencies at your destination. As far as I am aware, those bands and frequencies can be found on websites like here.
Hope this helps 😀
Cheers
