Six months after debuting its in-house C1 modem with the iPhone 16e, Apple has followed up with the C1X modem on the iPhone Air.
The new baseband fixes the shortcomings of the initial version, supporting faster speeds while still being extremely power-efficient.
C1X delivers both speed and efficiency
After years of rumors, Apple launched its in-house C1 modem with the iPhone 16e in February 2025. It stood out for being the “most power-efficient modem ever in an iPhone,” with a claimed power saving of up to 25%. Besides 4G and 5G, the modem also integrated satellite and GPS connectivity for deep vertical integration.
Thanks to the unparalleled efficiency, the iPhone 16e offered the longest battery life ever for an iPhone despite a modest battery capacity. Yet, the C1 modem fell short in one key area: missing support for mmWave 5G.
Apple’s second modem, the C1X, promises to deliver better speed. The company claims it is “up to 2x faster than C1.” And yet, the modem still only supports sub-6GHz 5G. Even so, Apple says it is faster than the iPhone 16 Pro’s Qualcomm-supplied baseband.
What’s impressive is that despite supporting faster download speeds, the C1X consumes 3o% less power, making it the new “most power-efficient modem in an iPhone.”
Better power efficiency brings another benefit: reduced heat.
iPhone Air gets exclusive dibs on C1X modem
For now, Apple is only using the C1X modem inside the iPhone Air. It plays a key role in enabling the super-slim phone to provide all-day battery life. And while the lack of mmWave 5G might be a bummer, the iPhone Air should provide faster download speeds than the iPhone 16e.
Rumors point to Apple switching to its in-house 5G modem for the 2026 iPhone 18 Pro. If that happens, the company will likely use an even newer modem with support for faster speeds.
Real-world data points to Apple’s C1 modem holding its own against the iPhone 16’s Qualcomm modem. And the iPhone Air’s C1X modem should fare even better, especially with its other upgrades.
Rajesh has been closely following and writing about the latest happenings in the world of mobile for nearly a decade now. While he prefers Android, he does not deny the superiority of Apple’s products and ecosystem.
