Thanks for trying those steps and getting back to us, see32. It's appreciated.
Let's make sure that your carrier doesn't have an update for your iPhone: Update your carrier settings on your iPhone or iPad - Apple Support
Update your iPhone, iPad, or iPod touch - Apple Support -- Also make sure your iPhone is also up to date. The current iOS version is 15.4.1. You can see which iOS version your iPhone is on under Settings > General > About.
If it seems to happen only while you're in the office, this may be related to interference: Resolve Wi-Fi and Bluetooth issues caused by wireless interference - Apple Support. Instead of focusing on any Wi-Fi issues, apply a few of the steps in this article to check your carrier connection. As an example, do the number of bars drop at the time the other party mentions the noise? You should also avoid using your iPhone near common sources of interference, such as power cables, microwave ovens, fluorescent lights, wireless video cameras, and cordless phones as these affect not only Wi-Fi and Bluetooth signals but carrier signals as well.
Feel free to get back to us with any questions or problems you may have.
All the best.