Best Practice for inbound messaging

Our Boy Scout Troop is embarking on a wilderness hike and we'll have 3x Garmin InReach Explorers, one for each hiking patrol. We plan to send the usual updates, starting hike, ending hike on each day etc and using Mapshare so families can follow their Scouts. My plan is to turn off the ability to send messages or find the location of devices via Mapshare, as I don't want to have a parent or the extended family sending unwarranted messaging asking.... "how little Johnny is feeling?"

We will have Primary Contacts who will receive messages/updates, who will then distribute to family members. Plus these messages will appear on Mapshare. But the question I'm trying to solve for is, how does a Contact send an "unprompted" message to the device?

Per the below link and what I've read on the forum, I believe the only option is to establish a conversation thread via a TXT/SMS message at the beginning of the trip, this assigns a phone number for several weeks, which can then be used to receive inbound messages. Is that a correct understanding? If the inreach sends a new pre-set message, is the same phone number used?

https://support.garmin.com/en-GB/?faq=o4sYSXP4LC8KhFNWJEVPI7

Alternatively, if we use email. Could one of these Contacts pull up an old email, open the message link and send a message? Would that work? Would it make sense on the inreach and/or appear on Mapshare and be logically?

0 twolpert over 6 years ago

Your understanding of replying to an SMS message is substantially correct. But there is a subtle misconception buried in there which might cause problems. Sending an SMS message does not assign a phone number to the inReach device itself. Rather, it establishes a relationship between the number from which the Garmin server sent the message (from the inReach to the mobile phone recipient), the recipient's phone number, and the ID of the inReach device. If the recipient replies to the SMS message, the reply goes back to the number from which the Garmin server sent the original SMS, which then lands at the Garming server. The Garmin server matches up the number on which it receives the reply and the mobile number which sent the reply to find the inReach device. The server then forwards the reply to that inReach device. This relationship only persists for a few weeks. If it's gone by the time the reply is sent, the reply will be undeliverable.

The bottom line is that only a phone which received an original SMS from an inReach device can reply to it. Other phones cannot use the number from which the inReach message appears to have come in order to send messages to the inReach. It is best to assume that every message sent from the inReach will use a different, randomly selected "phone number" for the outbound SMS messages. In practice, the fact that each message may appear to originate from a different number has no effect on the recipient's ability to reply to the SMS from the phone which received it.

Best practice for allowing replies to the inReach from mobile phones: Send a message from the inReach to each such phone before starting your trip. This "primes the pump" for replies. It is OK to send an SMS with multiple recipients for this purpose. That is, it is not necessary to send a separate, individual message to each phone.

I don't now the answer with regard to e-mail. In the case of e-mail, the reply is mediated by the Garmin web site. The link in the e-mail refers to the message, not directly to the inReach device. This implies that the Garmin server must still have a record of the message in order to be able to reply to the proper device. I don't know how long those message records are retained. I did just check one of my own, sent on April 16, 2018. The message record still exists, so it's not like they disappear as soon as you access the message, or the next day, or something like that. So my recommendation for best practices for e-mail would be the same as for SMS - prime the pump with a message to each e-mail address immediately before leaving on your trip.

0 CowboySlim over 6 years ago

I concur with the above post. Additionally, IM(not so)HO, it is all about SPAM prevention.

0 twolpert over 6 years ago

Thanks for mentioning that, CS. Both sent and received messages will be charged against your plan. By limiting the ability to send messages to your device to those who have received messages from it, Garmin protects you from paying for spam or other unsolicited traffic. This is also why you must authorize MapShare users to send messages to your device. All aimed at leaving you in complete control of what you pay for.

0 Stewart over 6 years ago

Thank CS and Twolpert. Yes the goal is to limit Scouting Parents from spamming us. No need for communication unless its emergency related in both directions and for basic trip updates on a daily basis. You guidance helps determine how best to support this while turning off messaging in mapshare.

0 Outcast_Six over 5 years ago

Stewart,

How did it turn out for you guys? Or have you not taken your trip(s)?

Our troop was scheduled for a 2018 Philmont trip, but we became refugees due to the wildfires. We are scheduled to go this summer (2019) and are considering a similar method that you described in your OP. We plan on getting in many miles this Spring/early Summer before we go as we did last year along the AT, Dolly Sods, etc in our local area and the lack of communication seemed to work out ok on short 2-3 day jaunts.