Apple has introduced the C1X modem as part of its 2025 silicon lineup, debuting in the new iPhone Air. Building on the previous C1 modem, C1X improves efficiency, doubles 5G speeds in some scenarios, and contributes to making iPhone Air the most power-efficient iPhone yet. By designing its own modem, Apple continues to optimize connectivity alongside its A19 Pro and N1 chips.
According to Apple, the C1X offers up to 2x faster performance compared to C1, while using 30 percent less energy overall. It also outpaces the modem in iPhone 16 Pro under the same network conditions. Apple describes C1X as the most power-efficient modem it has ever placed in an iPhone, underscoring its role in balancing performance with battery life in thin and lightweight designs.
The C1X supports 5G sub-6 GHz and Gigabit LTE, but unlike Apple’s iPhone 17 Pro models, it does not include mmWave bands. This decision aligns with the design goals of iPhone Air, where space and efficiency are prioritized over peak mmWave speeds. In everyday use, sub-6 GHz provides broad 5G coverage with consistent performance.
Apple has also streamlined carrier support with dual eSIM capability and the removal of the physical SIM tray. iPhone Air users can now store and switch between multiple eSIM profiles for easier travel and carrier flexibility. This change, combined with the C1X’s energy savings, helps simplify connectivity while extending battery life.
The modem also works alongside satellite features that Apple first introduced with iPhone 14. With C1X, iPhone Air supports Emergency SOS via satellite, roadside assistance, and satellite messaging in supported regions. By refining efficiency, Apple ensures these safety features remain reliable even when traditional networks are unavailable.
The C1X integrates closely with the A19 Pro and N1 chips. While A19 Pro powers the CPU and GPU, and N1 handles Wi-Fi 7, Bluetooth 6, and Thread, the C1X focuses on wide-area cellular and satellite connectivity. Together, these chips form Apple’s most advanced connectivity stack to date, covering both short-range and long-range communication needs.
Strategically, C1X represents the next step in Apple’s in-house modem program. Rather than relying on third-party suppliers, Apple is building its own cellular solutions that fit tightly into its broader silicon strategy. With each generation, the company gains more control over efficiency, performance, and integration across devices.
With iPhone Air as its launch device, the C1X modem marks a significant upgrade in 5G speed and efficiency. Combined with the A19 Pro and N1 chips, it ensures that iPhone Air delivers not only thinness and lightness but also reliable, advanced connectivity that keeps pace with Apple’s expanding ecosystem.
