I’ve seen some misinformation that doesn’t address the question and no answers.

First the misinformation: if you live in the US and work in an at-will state, your employee handbook will dictate what company can or cannot do. In most cases, especially for larger companies, there will be explicit language allowing the company to do whatever they on anything that uses their software or tech they’ve provided (eg your phone you use for company email). Two-party consent doesn’t apply in these cases because you signed the employee handbook or were informed it was a condition of your employment. Since it’s at-will too bad. However, even with these power, most companies aren’t doing shit unless you’re fucking up. Give someone a reason to throw IT or security at you and it could happen. Chances of this are higher at either larger companies or small companies with power-hungry idiots running the show. I have worked at all kinds and see all sides. If you are not in the US or live in a state with employment contracts (not at-will), this might not apply unless you signed away those rights and there is nothing getting them back. It’s always a good idea to be friendly with IT and security to learn what they do and do not do.

As to your question, do companies fingerprint employee voices, most likely not. In the US I’m at-will states you don’t need to go through all the trouble of tracking voices for termination or legal action. In the private world, this is a very secrecy-oriented problem (eg Apple trying to keep the lid on surprise and delight) so it wouldn’t happen except for very large scale. In the public sector, you genuinely should be afraid of this because government agencies are sucking down all the data they can. This is true around the world. More importantly, they’re all incompetent as fuck and being sold shitty software that doesn’t work so they’re misusing data like this for incorrect identifications.

In general, if you want to be anonymous, practice good operational security. Changing your voice never hurts. It’s not a bad idea to be safer (unless you’ve chosen a tool that can be easily reversed). You should also use phone numbers and hardware that can’t be traced back, which is a bit harder.