Apple is introducing a new iPhone Handoff feature with iOS 17, allowing users to share a single phone number across two iPhones. This functionality requires carrier support and may involve associated fees. Initially, this feature will be limited to T-Mobile in the U.S. and Deutsche Telekom in Germany upon iOS 17's release. To utilize iPhone Handoff, both iPhones must run iOS 17 or later, be connected to Wi-Fi, and signed into the same Apple ID with specific services enabled. Users can set up one iPhone as the main device and the other as secondary, sharing the same number. Certain carrier services, such as call forwarding and caller ID, can only be managed on the primary iPhone. The system automatically swaps the active iPhone when one device is unlocked, confirming the switch with a notification. Only one iPhone can actively use the phone number at a time with this feature. While some Wallet items like payment cards and car keys work on both devices, others may be device-specific. iPhone Handoff supports Dual SIM as long as both eSIMs are from compatible carriers, switching simultaneously. This feature remains active until deactivated by contacting the carrier. iOS 17 is scheduled for release on September 14.