Okay -- I spent some time this morning experimenting. Most of this will be specific to the Apple/Globalstar combo. I tested using an iPhone 16 Pro (A3083) and a DiveVolk SeaTouch 4 MAX PLUS.
I have been meaning to test this but it is a little difficult as you need to be out of coverage range for all cellular and wifi before satellite will even be enabled.
You do for "real" use -- but numerous sources (and some experimentation) indicate that the test capability available through the Settings app does actually perform at least satellite reception and reportedly two-way. Although it doesn't give any indication of signal strength, it does pass/fail.
I started by making sure I could pass and fail -- pass was if the test mode reported successful connection to a satellite; fail was if it reported being unable to do so. I tested failure by blocking line-of-sight to the indicated satellite position two ways: by being inside (but adjacent to my outside test location) and by constructing an RF shield and using it at the outside test location (yes, I made a tinfoil hat for my phone.)
It depends on your cell provider also. If you have T-Mobile they will have direct to cell satellite texting available for all of their customers in July and voice and data within 2 years. If you have any other carrier they are using Globalstar geosynchronous satellites that are in a much higher orbit, which is why you have to find the satellite direction before being able to send a message.
I'll get back to T-Mobile, but first a misconception: Globalstar isn't in geosynch; they're about 876 miles up, as opposed to Starlink's 342 miles. Way different from geosynch at 22,236 miles. Globalstar, however, only has about 48 satellites in their constellation, which is more of why you need to point at whichever is currently in best view.
(Starlink has about 7,500 currently in orbit and working, though only about 13 (planned to be 330) have direct-to-cell radios.)
Back to the experimenting: after proving I could pass and fail, I put the phone in the housing and repeated the steps. Short answer: I was able to successfully communicate on every attempt from within the Divevolk housing when I was not taking steps to block the signal.
I'm going to pause and emphasize this again:
Remember that it doesn’t work anyplace they’ve decided it wont work. It’s not like a satphone that might sort of work at the edges of coverage and maybe you can reach AFRCC/USCG/Global Rescue/Constellis/etc. even though it’s not supported — if Apple doesn’t think you’re in a
supported area it won’t even try.
That does not cover direct to cell satellite communications though Starlink with T-Mobile. It only applies to Apple’s contract with Globalstar. The Starlink geographic coverage limits will be set by the carrier and DTC providers and will be different than coverage from Apple.
What I want to ensure people consider with the current Apple/Globalstar is that it's up to Apple's undisclosed logic whether the phone will even try; if you're not where it thinks it should work, it won't let you attempt. There's no "best efforts" mode.
We don't know precisely yet with the Starlink capability, although T-Mobile
is clear that their offering currently only covers "the Continental US, including Puerto Rico and parts of southern Alaska" and that they hope someday to cover international and offshore. I don't think we can draw any firm conclusion about whether the phone (T-Mobile, Starlink, etc.) will decide whether you're permitted to try -- but IMO it's likely there will be artificial restrictions, even if only for regulatory compliance reasons.
I expect to be in the T-Mobile test population later this summer, and I'll experiment with the Divevolk case then.
IOW from the previous, though: if you re bobbing in the waters of Lake Michigan, it may work. If you are bobbing in the waters of most of the rest of the planet, chances are pretty low that either will work for you. Personally,
discussions.apple.com
