@robinraig
I have a Captel landline at home that has a jack on the side and I loop Ear Links over my hearing aid. This eliminates any buzz and brings the voice right to my ear. Can order online. Not sure if the standard office phone has a jack and if it does, you need to find out how big it is....example it may be 3 millimeters. I understand the buzz problem and even supposedly Tcoil compatible and hearing aid compatible phones are ineffective. There are also neckloops that you can wear but they also have to be plugged into a phone.
Consider ordering a Captel phone for home...you can read the captions and hear at the same time. Captel phones work for businesses but it depends on their phone system and whether your company is willing to accommodate you. There is no special number involved. Since my hearing loss is profound, I can no longer hear on the Captel with an earlink or neckloop. You may not need one.
My Tcoil is set to have some regular mic sound which means I can hear on the phone but also get some hearing if someone is next to me speaking to me.

Hope this helps
Regards from Florida Mary