DeLorme InReach Communicators - Global messaging and GPS locator unit
The Alpine Club has 2 devices available for members to hire.
There is a charge of £12 per week during the time it is in the renter's possession, plus usage costs.
The GPS uses the normal GPS satellites, while the messaging is through Iridium.
The messages can be sent to email accounts or to cell phones.
The messages have a max length of 160 characters.
The battery seems to last a week.
The advantage is to have a single piece of equipment which does the job of altimeter, GPS with very good track log (you don't need to enter the way points separately, but just reverse the track) and communicator.
The messages give your GPS coordinates, as does the emergency locator software, so your position can be followed with each message as well as by a track log, if you want.