Just two weeks after going on sale, the iPhone 18 Pro Max has already been hit by network disconnection issues in the US. US carrier AT&T has confirmed that some US versions of the iPhone 18 Pro Max are experiencing abnormal cellular network failures, and the two companies are jointly investigating. Affected devices intermittently or completely disconnect from the AT&T network, making it impossible to make calls, send and receive text messages, or use mobile data normally. In severe cases, even emergency calls cannot be made, and the phone often automatically enters SOS emergency mode.
Thousands of complaints, and upgrading to the latest version doesn’t help either.
The iPhone 18 Pro Max went on sale on September 18, and so far as many as several thousand user reports have accumulated on platforms such as the Apple Support Community and Reddit. The earliest reports of the issue were on It was already reported by MacRumors on September 25.Some U.S. users’ 18 Pro Max phones can’t connect to AT&T’s network; calls, texts, and data are all completely dead, and eSIM activation is also problematic. A week later, on October 1, AT&T sent a text message directly to users, saying: “Hello, this is AT&T. You need to take action: your iPhone 18 Pro Max has an important Apple software update. Some phones may be unable to make calls, send texts, or use data, including calling 911. Please update to iOS 27.0.1 immediately: Settings > General > Software Update. If you have questions, contact AT&T or Apple.”
But upgrading the firmware did not fundamentally solve the problem, and a large number of users reported that network issues remained after updating to iOS 27.0.1. The iOS 27.0.1 release notes show that this version only fixed Face ID-related vulnerabilities in the iPhone 18 Pro series and made no mention of fixing network issues. According to an internal carrier email, officials themselves admitted that the update was only meant to reduce subsequent risk and could not save devices that had already been affected.
Apple admits: if affected, you can only replace the device.
On October 2, Apple, through a statement, officiallyAcknowledge the problem.The statement said: “We’ve confirmed an issue affecting a small number of iPhone 18 Pro Max users on AT&T’s network that may cause devices to lose service and be unable to make calls. We released iOS 27.0.1 earlier this week and strongly recommend that all iPhone 18 Pro Max users update immediately; we’ll also release a carrier settings update today. Together, these two updates are intended to help prevent this issue from occurring.” The key point is in the second half: devices already affected cannot be recovered by a software update and must be replaced entirely. Apple recommends affected users contact Apple Support or AT&T, or go directly into an Apple Store or AT&T retail location, where they will be replaced for free.
This time, the blame might not be on Apple; the U.S. model is the only one that uses a Qualcomm modem.
The scope of this incident is quite intriguing: only the US version of the iPhone 18 Pro Max on AT&T’s network. And the US version 18 Pro Max is the only model among this year’s new iPhones still using a Qualcomm modem. The same-generation iPhone 18 Pro and iPhone Duo use Apple’s in-house C2 modem globally, and the non-US 18 Pro Max also uses C2; only the Pro Max sold in the US is the exception. A teardown confirms that the motherboard of the US version 18 Pro Max has a modem marked Qualcomm SDX80M and an SDR875 RF transceiver, while when Apple’s official specs page is switched to the US region, the C2 text in the 18 Pro Max column vanishes into thin air, but the 18 Pro column still has it, which matches the teardown results.
Why only the US version still uses Qualcomm, Apple has never publicly said. The prevailing outside view points to the contract: in September 2023, Qualcomm announced it had signed a modem supply agreement with Apple covering smartphones launched in 2024, 2025, and 2026. The iPhone 18 series launching in 2026 falls exactly within the agreement period. There is currently no direct evidence that the network issue is caused by the baseband.
Some people got hit, while others were completely fine.
Not all AT&T users are experiencing disconnections. In the MacRumors comments section, some readers reported two weeks with zero problems, with reception even better than on their 17 Pro Max; others said Face ID became slower in low light while the network was completely normal, and suspected it was a hardware quality issue in another batch. In other words, this time only a small number of units are affected, not an entire batch failing, but if you get one, the whole phone turns into a brick and can only be replaced—it’s a gamble of luck.
For those of us in Taiwan, there is actually no need to worry. Currently, the official confirmation is only that this issue has been found on the 18 Pro Max on the AT&T network, and no problems have been reported for other models or other carriers. All iPhone 18 Pro series models in Taiwan are equipped with the C2 Modem, so you can use them with peace of mind.
Source:MacRumors
Source: KOCPC Chinese