I have a bit of a history with Telus regarding these services, which I'll briefly explain before the problem.
I have spoken to customer service representatives that have told me HD Voice/VOLTE should be no problem with my phone. After testing, we have confirmed that neither work. They told me that I was to enable the service on my account and then it should be ok. I got the email indicating that it was enabled and I restarted my device and tried it. It has never worked. I spoke with another rep who told me that my plan was a business only plan(I received this through retention for another issue) and that I had to get a customer plan which would be double the cost per month than what I pay now for the same service but that would fix the issue. I obviously protested this because I shouldn't have to change my plan to get services that I am already paying for. Also, I used to have a Moto X and Iphone SE which I got through Telus and the HD voice was fine. I have another ongoing issue at my office where I am missing calls when connected to the LTE network here. I have had a Telus wireless technician come to my office to see what the issue is. While he has confirmed that I am indeed missing calls while connected to the LTE network (even using his phone) he doesn't know the cause. He also told me that I cannot use VoLTE/wireless calling because I did not buy the phone from Telus stock. This has happened with all of the previous phones. I had bought a Huawei Honor 8 and had the issue, then tried to get customer service help but was told the phone was not supported because it wasn't a Telus phone. So, I sold that and got an S8 which I'm using now because it was told to me that it was compatible with the Telus network.
In sum, I am unable to get these features working, spent quite a few hours getting no answers and being told to pay more for a solution.
While I love Telus and am very appreciative of the support they have given me, something has to change. I have been a customer for over 15 years and I feel like the answer I'm being given here is to pay more money. If this is the only solution for my issues then I'm sure we will be parting ways but I would prefer to stick with Telus!
If the phone you purchased from another source does not have the Telus firmware loaded, then you may well be in the situation where all the most recent features are not supported.
Edit: VoLTE is available to at least one individual I know on a business plan.
Most retentions plans and all Employee plans are business plans, as there is more latitude to adjust the content of the plan. However business plans do not offer the same options as consumer plans. For instance, Easy Roam was made available to consumers long before it became available to those on business plans.
For instance, Wi-Fi calling is not yet available on Android phones.
After some searching, it looks like unlocked phones have issues connecting to VoLTE in many countries compared to carrier versions of the device. The problem may be firmware related but looks more like it's also related to the unlocked devices and their IMEI not being registered with the carrier as one of their devices. None of the discussions online have shown there is a solution for this short of getting the phone from the various carriers out there.