One number, two iPhones
As documented by MacRumors, iOS 27 allows a single phone number to be shared between two separate iPhone devices, with users switching between them as needed. The mechanism is presumably similar to how an iPhone and Apple Watch can already share the same number. Carrier support may be required, so real-world availability could vary. The feature is particularly relevant for anyone planning to pair a traditional iPhone with the foldable iPhone expected this fall.
Alarm volume and AirPlay
Two other improvements surfaced in iOS 27 documentation: alarm volume will be configurable independently from the system's general volume level, resolving a long-standing limitation. According to 9to5Mac, AirPlay connections to Apple TV and HomePod will also be noticeably faster. These are the kinds of refinements that never make keynote headlines but meaningfully improve daily usability.
These tidbits fit within Apple's stated philosophy for iOS 27: a refinement-focused release rather than a reinvention, with hundreds of accumulated fixes and performance improvements as the throughline.