How iOS 27 Dual-iPhone Handoff Operates
Reported by MacRumors for iOS 27, iPhone Handoff allows two distinct physical iPhone models to share a single carrier phone number and cellular subscription simultaneously. Rather than basic Bluetooth forwarding or audio relay, this protocol coordinates dual eSIM registrations directly with the mobile network operator's IP Multimedia Subsystem (IMS).
When an iPhone user brings their companion device within Ultra-Wideband (UWB) range or taps a Continuity notification, Apple Continuity dispatches a cryptographically signed push-to-switch token. The carrier virtual core acknowledges a SIP re-INVITE, seamlessly shifting real-time RTP voice packet streams with 0 dropped audio samples and typical transition latencies under 150 milliseconds.