SOLVED Call box will not open entry door with iPhone

In my case, I did not have to restore my network settings or anything after I did the SIM card switch from Sprint to T-Mobile at the store. My phone was once again able to unlock the front door through the call box system. I have an iPhone 11, current iOS 14.6.

I really appreciate your posting. I have had the exact same issue with my iphone 11 with IOS 14.6. Before that I was able to buzz people into my apartment building by pressing #6 or #9 and it suddenly stopped working. I had the callbox company come out to try and resolve the issue and they could not help. I am also a Sprint customer and today I went to TMobile to swap out my SIMM card for a TMobile SIMM card. I was able to unlock the door with my phone after the swap.

Thanks for posting that. I will give it a try. There seems to be many complaints about this problem but nobody seems to have an answer.

I had such hope this would work for me, but it didn't. Did you need to restore your network settings or anything after your SIM card switch?