Apple has released a new version of iOS 15, albeit only one for recent iPhones. Clearly, Apple discovered a problem in iOS 15.1, because iOS 15.1.1 'improves call drop performance'.
While a terse changelog, we presume that Apple means iOS 15.1.1 reduces the likelihood of a call being dropped, assuming you do not lose signal mid-way through a phone call. As it stands, Apple is only rolling out iOS 15.1.1 to the iPhone 12 and iPhone 13 series, i.e. the following devices:
- iPhone 12
- iPhone 12 mini
- iPhone 12 Pro
- iPhone 12 Pro Max
- iPhone 13
- iPhone 13 mini
- iPhone 13 Pro
- iPhone 13 Pro Max
Apple's changelog makes no mention of any other changes, unlike iOS 15.1. Hence, it seems that iOS 15.1.1 is nothing more than a bug fix for the iPhone 12 and iPhone 13 series. The next notable update for iOS should be iOS 15.2, which has reached Public Beta 3. You can sign up to try iOS 15.2 via the Apple Beta Program site. Apple is expected to release iOS 15.2 towards the end of November, or by early December.