Haven't checked lately but Satellite phone use was always rather expensive. Cost of the phone, subscription fee, and the biggy was cost per minute. Renting a satellite phone is an option also if it's something you'll seldom use. But the cost per minute will keep your calls short and just for the important stuff. We rented one a long time ago for a long distance sailing trip where we'd be days out of cell or vhf range.
I have a Garmin InReach. It is pretty awsome. Satalite messaging, tracking, and GPS unit in one waterproof package. I pre paid for 2 years when I first got it worked out to $12 a month.
For that I get unlimited InReach to InReach texting, unlimited 4 preset editable messages that you can send to email or any phone, and 10 other text messages or tracking uploads per month. There are more expensive plans as well. It also connects to my phone via Bluetooth so unless it is wet I use my phone for all it’s functions.
I like it so much we got a 2nd one as we spend a lot of time outside cell reception.
For the 4 pre set messages you can change them from a computer any time. Just so you get an idea of what they can be used for mine are: “just starting our trip”, “back from our trip and ok”, “delayed but all is ok”, “delayed and in need of assistance not urgent”
It also has a SOS button that notifies rescue services with your location and then sends tracking if you move until they reach you.