Real time display of current call time

Previously I was able to see how long I had been connected to a call. This is especially helpful if you are on hold with customer service and you want to know how long it has been since a real person spoke to you. I have an iphone 7 running IOS 15.5. Previous answers to this question suggest looking at the call info AFTER you have hung up. I want "real time" info during the call displayed on the screen. Another suggestion was to go into settings and then mobile data. These options don't exist in my settings menu.

Please advise!