Conference Call Problems for years with multiple iPhones on multiple operating systems, and multiple carriers

I have had an iPhone for years. Different models on different operating systems. Conference call feature on Apple IPhone is horrible to say the least. It’s Been an ongoing issue for years, and Apple seems to refuse to fix it. Each OS that comes out it seems Apple is more into adding new emojis rather than fix the conference call issues. Problem merging callers. Issue with showing who is on the call. Sometimes I have 4 people on talking but my phone only shows 1. Issues with merging where the whole call drops.