You should have no problem with that anywhere in the world as long as you keep it in an inner pocket. Perhaps pack wired earphones just in case you need to make a long call while keeping the phone itself warm.
Notably the battery should not be charged below about 5C. If you do, it will be permanently damaged.
This depends on the specific battery chemistry. The BMS should prevent the charging scenarios which would damage the battery. For some it's 0C not 5C. Some can handle charging below 0C.
Even the cheapest chips from TI and ST seem to include it. And modern cell phones often advertise extra-fast 20W+ charging, so I doubt they're using the cheapest chips.
They've been the only ones that don't just turn off in really cold temperatures, even without babying them in warm pockets.
The general ruggedness is also pretty good to amazing, depending on how fragile your previous phones were. For example: it survived a ~10 meter (32ft) drop on rocks, whereas everyone was convinced it was done for.
To be honest I first thought it would be a gimmick, but being able to see heat / rough temperature degrees has proven itself quite useful.
But you don't really realize it until you have it available. It's kind of like having another sense available to you.
Random examples of where it was useful:
- finding shitty chargers/electronics which were really hot while doing nothing -> wasted power
- spotting a water leak before it was visible (think cold spot in the middle of the ceiling)
- checking car tire alignment (one side hotter than the other)
- finding buried hot water pipes
- finding where cold air is leaking in during winter
- spotting damp areas
and probably others that I'm forgetting right now
I had that in my hometown in eastern France at 800m altitude, a town a few km away has a record of -41. -15/-20c was almost a yearly occurance when I was a kid
Once I was stuck with a ridesharing car opened and off in -20C because my old samsung s8 throttled so bad I couldn't even reboot it. It was completely unresponive with the flashlight still on discharging it even faster.
I couldn't leave the car too, being responsible for damages during the rent.
After a bit of time I remembered that to force shut down newer androids you have to hold volume down and power. Why would they not keep it as a long press is beyond me.
Also to communicate on-the-fly decision-making to inform potential SAR - "I'm making good time, going to head up this extra peak before continuing the planned route."
I'm happy to have a cell phone backup to the inReach, but I don't see this Starlink offering as a replacement. That goes double if you're out in winter. Phone batteries aren't great in the cold.