About OnePlus' support

I try to use a phone as long as possible, the previous one kept up with me for 3 years. Then, I was looking for a new device for a long time, taking in account every aspect I consider important. One of them was support of the device. Support as time how long the phone receives new software updates, support as available community where I can discuss things and support as if I report a problem I face, somebody tries to help me. This is why I choose OnePlus.
I read their system supports VoWifi. When I received the phone I was looking for this option among the SIMs settings, but couldn’t find it. It isn’t a deal breaker, but if they state that’s available, I want to use. So I contacted them on June, 28.
Since then, there were a few system updates and I installed the (current) latest as well, Open Beta 19, where the VoWifi switch appeared, however, that has no effect. I configured to prefer Wi-Fi calls and VoLTE is only a fall-back option. Still, my phone cannot establish the connection and after a few minutes the VoLTE icon appears. I was curious if there is any limitation on the carrier side and I was told (multiple times) Telekom Hungary has no such a thing, if a device supports Wi-Fi calls then that can be used, no other requirements are set.
OnePlus called me on the 3rd of November, pushing the issue back to my carrier. When I explained that I already talked with my provider the service agent told me they’ll call me back soon. But since then, I didn’t receive anything from the team.
I checked if I place my SIM card into an other phone then I can use the mentioned feature and it works with Samsung Galaxy S20. It narrows down the issue to OxygenOS. OnePlus. I shared this finding with the support team but still no answer.
151 days since I first contacted them. 5 months. 23 days since I received the last message; so I thought I’ll follow up with them on chat. It was a good idea because Levi George was helpful and confirmed my problem is solved in the latest stable release of Oxygen OS, in 10.0.10 EU. Guess what I did the day before yesterday. Yes, I formatted my phone and flashed the new OOS version.
I’m happy to see the service is really available and if I place calls they go through Wi-Fi.
Thank you OnePlus.