On Wednesday, May 2, 2018 at 12:53:41 PM UTC-4, wrote:
You can get a (very limited) non-emergency messaging option for a PLB, not free, but a lot cheaper than SPOT: http://406link.com/ - these "messages" are content-free, but by pre-agreement with your buddies they could mean "I'm OK but need a retrieve". (I've suggested to them to add some bits to the message data packet to allow selecting between several different preset messages, but they've apparently ignored me.)

"Note: 406Link.com is a one-way communication tool designed only for Satellite Confirmation testing." So, hack away, but expect to be ignored.