As noted by Nicolas Lellouche, who writes for the French tech website Numerama, Apple has updated its tech specs pages for the iPhone 18 Pro and iPhone 18 Pro Max to clarify which models are equipped with its new C2 cellular modem and where.

Apple now says the iPhone 18 Pro has a C2 modem worldwide, while the iPhone 18 Pro Max uses the chip in every country except for the U.S.

According to a tipster known as @itspdfu, who has been digging through Apple's software updates in recent weeks, iOS 27 code reveals that the iPhone 18 Pro Max is equipped with a Qualcomm modem instead of the C2 chip in the U.S.

Apple has yet to provide an explanation for this modem difference, so we can only speculate for now. In 2023, Qualcomm announced that it would supply Apple with smartphone modems through 2026, so perhaps Apple is equipping the U.S. version of the iPhone 18 Pro Max with a Qualcomm modem in order to honor this agreement in a minimum way.

Apple's C2 modem supports ultra-fast mmWave 5G in the U.S., unlike its previous-generation C1 and C1X modems. Qualcomm modems in the iPhone 12 and newer already supported mmWave 5G in the U.S., so Apple is playing catch up here. Apple said the C2 delivers "meaningfully faster uploads" compared to the C1X while consuming 15% less energy.

Apple's first-generation C1 modem debuted in the iPhone 16e in February 2025, and the second-generation C1X debuted in the iPhone Air in September 2025. Now, the third-generation C2 modem has arrived in the iPhone 18 Pro models, except for the iPhone 18 Pro Max in the U.S. as mentioned, as Apple's transition away from Qualcomm continues.

It is unclear which Qualcomm modem is in U.S. units of the iPhone 18 Pro Max, but the Snapdragon X85 is most likely. Over the coming weeks, real-world performance tests should show how the C2 and Snapdragon X85 stack up.

Apple's foldable iPhone Duo uses the C2 modem worldwide.