iPhone 17 Pro Max loses cellular service after LTE to GSM fallback

Subject: iPhone 17 Pro Max cellular failure during GSM fallback — request for baseband engineering review

My iPhone 17 Pro Max (iPhone18,2, iOS 27.0.1, baseband 2.10.04) fails USSD after fallback from LTE to GSM and, after a second attempt, temporarily loses cellular service across RATs. A control iPhone 16 Pro Max on the same iOS version and carrier completes USSD and a voice call. I have event timed sysdiagnose archives for both devices and an engineering comparison report. I'm ready to provide logs to Apple engineering to attach them to this case and escalate for cellular/baseband analysis of GERAN cell selection, RR/RACH access, and LTE recovery. The report identifies what the logs establish and what still requires baseband trace decoding. Please provide an official secure upload method for the archives and the case number.

Posted on Oct 18, 2026 4:01 AM

2 replies

WheelieNick

Level 9 (74,110 points)

Oct 18, 2026 6:47 AM in response to maxim_belousov

Apple is not actively participating on this user to user support forums. If you want to escalate this through apple support., please Contact - Official Apple Support

lobsterghost1

Level 10 (233,174 points)

Oct 18, 2026 7:27 AM in response to maxim_belousov

Where do you live where there is still any GSM, which is in reality 2G cellular service? In most of the world 2G has long been turned off. Even 3G service is rarely supported in most places in the world.