In Canada, the iPhone 18 Pro Max uses Apple's C2 modem, while iPhone 18 Pro Max models in the United States have the Qualcomm modem.
The other day I was in Erin, Ontario for a wedding (a pretty remote area).
My iPhone was struggling for 5G service while my wife’s S26 Ultra was just fine.
My wife's S26 Ultra is on Qualcomm.
Just something to know if you’re a Canadian