I'm retiring my SPOT and bought a used InReach SE. My SPOT subscription came up at $180 this year. No thank you. (Anybody want a SPOT I or SPOT II? Make me an offer!)
My InReach cheapo rate costs $15 per month (that's $180 for the year), but then tracking and texting costs extra--per track point and per text message. But for the few hikes I get in these days, an extra $5 for the day isn't a big deal.
I carried a friend's Iridium phone on several extended trips, and it is like the SPOT -- does not work when no satellite is in view. It always worked on summits and wide-open areas. But down in a valley, I'd have to wait a while before it would connect. Or I'd connect and be talking, and the connection quality would fade out and then drop the call. Wait more minutes, then try again--the screen shows when a satellite is available.
My SPOT could never get a signal out below Lone Pine Lake -- the canyon is just too deep and narrow, so satellites are few and infrequent. The InReach will not blindly send tracking points like the SPOT does. Instead, it waits for an available sat, and then sends. So it's tracking is more dependable. -- I need to try it out on the Whitney Trail to prove this out.
Nice thing about InReach texting, too, is that it waits for satellite before it transmits your text. So in that way, it is actually better than the sat phone.
You don't need that sat phone. Just go with a cell phone, or use a texting satellite unit if you want to spend all that cash.