...is xhtml.weather.com. A long time ago I had a 30MB data plan and this was one of a few websites that continued to work after running out of data and getting paywalled, although most of the graphical assets were stored on a different domain and thus didn't load post-data bucket depletion. m.us.yahoo.com also used to work, but that was plugged in 2014.
TCP port 53 used to also be wide open, but from what I gathered on various forums, that was patched during the last major VoLTE outage. Two other users commented elsewhere on this story that this port (and it's UDP counterpart) as apparently still open on Verizon Wireless. However, I'm unable to confirm this paragraph.
Well, from a customer-facing perspective, speed tests on unactivated SIMs would be useful for determining what one can realistically expect for network speeds at a given location/time. A very minute "try before you buy".
Due to the way GSM/UMTS/LTE networks perform, there's no performance gains to be had in unconditional whitelisting of speedtests, since the air interface (wireless last mile) will ALWAYS be the primary bottleneck.
That whitelisting for speedtests also applies to unactivated SIMs and prepaid SIMs without active service (e.g. due to nonpayment or zero balance.)
I used to keep a spare phone lying about with an unactivated SIM while I had a prepaid SIM, and discovered the speedtest whitelisting was unconditional. I never thought to dig any deeper into it, although I suspected this type of thing was possible all along.
Glad to have my suspicions confirmed without having to risk my ass.
You should probably look into what you agreed to send Microsoft in the EULA
Surprise! I did. And maybe I'm not as paranoid as you, but seriously, this is fairly standard stuff for any software that has built-in telemetry. Do you know why telemetry is important? Because it shouldn't take four years to fix the next Windows Vista. If Microsoft fucks up a UI decision, they need to know quickly and have the changes rolled back or fixed in the next update. Not four years later.
Even if you want to push the "but Stallman said it's 1984!" argument...
Now, run along now, and make sure to refit your tinfoil hat because Wi-Fi's giving you brain cancer that can send your throughts to the NSA or whatever paranoid conspiracy crap you're buying into.