Telus doesn't offer VoIP phone service. If you get home phone service through Telus and have fibre, you're going to get an ONT or if SFPs are even available in your area, you'd get a Telus gateway that has POTS built in. SFPs are not available in many areas so you may end up getting an ONT anyways. Telus would not offer any assistance or support with your third party router and you'd be on your own to get it set up and to troubleshoot it if there are any issues. If your router doesn't have POTS/RJ11 jacks on it then it won't work for home phone service either.
If you get actual VoIP service through another provider that doesn't care what internet provider is used, and the VoIP phone uses standard ethernet or PoE to connect, then yes that would work. I work from home and have a VoIP phone that I brought home from work as my employer switched to a commercial VoIP provider for the entire office a year before Covid appeared. Works fine connected to my Telus router that is connected to an ONT. I also have home phone service connected to my ONT and I've had absolutely no issues with it either.
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