I didn't have bad call quality to begin with. Nothing in the release notes suggests that call quality has been improved, unless you're using Bluetooth in which it says: "Improves Bluetooth performance and connectivity with 3rd party accessories"
https://www.macrumors.com/2016/12/12/apple-releases-ios-10-2/
Also, you've posted quite a bit lately regarding call quality. But I don't recall you elaborating much on it. Are you using HD voice? Is your cell signal low? Is the person you're calling also using HD voice?
The reason I ask is because of scenarios like this: My mom used to have an iPhone 5s on Verizon calling somebody who has an iPhone 6s on Sprint and she told me that the call quality was horrible. However, she has updated to an iPhone 7 and now when she calls that same person she says the call quality is much improved to the point she can actually understand what is being said as this person has a habit of mumbling.