Thread is an IPv6-based network protocol designed for low-power Internet of Things (IEEE 802.15.4-2006 WPAN) devices and the iPhone 15 Pro and iPhone 15 Pro Max just released by Apple Supports the Thread mesh protocol, which is not included in the iPhone 15 and iPhone 15 Plus.

Thread is a new mesh network protocol that does not rely on other 802.15 mesh network protocols (such as ZigBee, Z-Wave and Bluetooth LE). It can improve the connectivity and responsiveness of connected products, and is suitable for people using the Apple ecosystem at home. It will be of great help to users.
Apple said that iPhone 15 Pro is the first smartphone to support Thread radio technology and can directly control smart home products that support Thread. Note: HomePod mini has previously added Thread connection function, but other Apple devices do not.
In a press release about the iPhone 15 Pro, Apple explained: Thread reserves space for the integration of home apps.
The main features of Thread include:
Easy to deploy and maintain—relatively simple to install, start up, and operate
Communication security—devices on the Thread network must be authenticated and all communications are encrypted
Stable and reliable - a self-healing mesh network with no single point of failure and uses spread spectrum technology to improve immunity to interference
Low power consumption — Thread low-power devices can sleep and run on battery power, often operating on a single battery for several years
Scalable—Thread networks can scale to hundreds of devices