First off, just to make sure people understand how the system works. If you are using a PLB there is no subscription. It is a program run and funded by your tax dollars. When you trigger an SOS, it goes directly to the Air Force and USCG Rescue Coordination Centers (RCC). They then coordinate the response, and route it to whichever agency (Federal, State, or local) is best able to respond. The downside of PLBs is that it is purely an SOS device. There is no way to send any messages regarding your exact circumstances or needs.

With InReach, one can send routine two way text messages. When doing solo trips, I will periodically send my wife a message letting her know I'm OK, where I am, and what my plans are. (There was a brief outage a couple of years ago when routine text messages were not going to ATT phones. Garmin said SOS messages were not effected.) When you trigger an SOS on an InReach, the message goes to the INTERNATIONAL EMERGENCY RESPONSE COORDINATION CENTER (IERCC). The IERCC is a private, for profit company, now owned by Garmin. When the IERCC receives an SOS, they determine where it is, and which SAR agency is appropriate for that location, and send the SOS on to them. They also immediately try to text back, to get more information. I don't know off hand of any hard statistics, especially regarding failures of the InReach system. My sense is that it has established a good track record.

I have knowledge of several instances when the system worked quite well. In one case, a party was attempting to ski across the Harding Icefield, and got caught in severe weather. In that case the IERCC directed the SOS to the 176th Wing of the Air National Guard (RCC, PJs, Pavehawks, and HC-130s). Using the text capability the RCC was able to determine the skiers had dug in and were reasonably stable (as long as their food & fuel lasted). Due to poor flying conditions, the PJs launched a an overland team to try to ski in. Later the weather cleared briefly, and a Pavehawk helicopter reached the skiers at about the exact time the ground party did. A happy ending.

In another case I have direct knowledge of, the IERCC notified the Alaska State Troopers (AST) of an SOS in the mountains near Anchorage. Coincidently it happened when local volunteer SAR teams were doing a table top training exercise, which immediately turned into a real mission. The AST helo launched but the area was too socked in. A ground team was also launched. The IERCC had tried to text the party, but had no immediate response. However, the InReach device continued to move up the mountain at a pretty good pace. The SAR teams became suspicious that this might have been an accidental SOS (as is known to happen with the older Delorme devices). The IERCC confirmed that indeed it was a Delorme unit. Ultimately it was confirmed that it was indeed a false alarm, and all SAR resources were recalled. Another happy ending. Overall the system worked well. There was good and prompt communication between the IERCC, the Alaska State Troopers, and the volunteer SAR teams.