Satellite feature missing?

There are regional restrictions that still apply due to regulatory requirements as detailed in the service.

• Use Emergency SOS via satellite on your iPhone - Apple Support
• Connect to a satellite with your iPhone - Apple Support
• About Messages via satellite on your iPhone - Apple Support

For example Messages via Satellite shows:

Messages via satellite is available in the United States, Canada, and Mexico.

Apple uses the GlobalStar satellite network. As with any Satellite device, coverage will depend the satellite network used. For a comparison of the major ones you can find more information here:

1. Iridium: Iridium's satellite constellation comprises 66 low-Earth orbit satellites, providing truly global coverage, including oceans and remote regions. This network is particularly popular for maritime use due to its reliability and ability to maintain connections in challenging conditions.
2. Inmarsat: Inmarsat operates a network of geostationary satellites that offer extensive coverage in the equatorial regions. While Inmarsat is known for high-quality voice calls, it may lack coverage in polar areas compared to Iridium.
3. Globalstar: Globalstar's network includes 32 low-Earth orbit satellites, providing coverage primarily in North America, parts of South America, and some European regions. However, it may not be as robust as Iridium or Inmarsat for oceanic communication.

https://crateclub.com/blogs/loadout/do-satellite-phones-work-in-the-ocean-a-comprehensive-guide?pb=0

Some cell carriers provide Satellite service that will use a different Satellite network. Your phone supports carrier provided satellite features as well, so check with your provider to see what they offer. For example T-Mobile is using the Starlink satellites for coverage with their satellite service.

About carrier-provided satellite features on iPhone - Apple Support

Apple doesn’t specifically document the details (that I can find), though there are various reports that satellite communications attempts from sufficiently far offshore are geofenced, yes.

I’d assume approximately within US territorial waters: 12 nmi / 22 km / 14 mi.

Ask Apple Support for the official details, and let us know.

you’ll likely find the feature no longer available outside of territorial waters.