Above all the other safety features that you can and should consider for your cruising boat, a satellite phone is the one that gives the most daily comfort. Pick it up and you can speak to anyone, and if it doesn't ring it means nothing disastrous has happened at home. The Iridium 9575 Extreme is the one I would pick today and so far, I haven't found any negatives.
Any old satphone is great for contacting family, but changing to an Iridium Extreme will give you an extra level of safety
For a start, it's very waterproof and very tough. A saltwater environment is not good for any technological gizmo. I have had the experience, even with the best of care, of salt water (or humidity?) getting into my satphone and shorting the connections. A satellite phone is for remote travelling, so once it goes, it's gone until you can get to a reasonably civilised port. In my particular case I was half way down the Red Sea.
It's also quite small - small being beautiful in hand-held devices of this sort. However, it's the safety features that really make this particular phone stand out.
It was the first satellite phone to offer the fully integrated services of customizable GPS, online tracking and emergency notification to your own family and/or friends. That feels good to me. Not only do I want the regulatory authorities to know when I am in trouble, I want someone with a vested interest in my safety to be chasing them up as well.
Being Iridium, it has world-wide coverage, which is important only if you are going to cross oceans. According to fellow cruisers who have used it as a tracking device it is excellent for that as well.
There are other things you can do with this phone too. If you also acquire an Iridium AxcessPoint, you can create a Wi-Fi hotspot on the boat. This enables you to use your smartphone and/or laptop to check emails and keep in touch with family, friends and colleagues.
The whole kit can be obtained for under $2,000, which might sound expensive at first sight, but a real boon if you can afford it, particularly if you have let the mooring lines go for extended cruising.
For lots more information, go to the http://www.iridium.com/default.aspx!Iridium_website.