reception of messages

My guess is the following: "InReach devices are designed to conserve battery charge whenever possible."

https://support.garmin.com/en-US/?faq=bn2ZEAhW2h8LdBQfK3c7b6

I think earlier DeLorme devices had passive listening, but Garmin intentionally phased that out and moved towards active listening. On some earlier Garmin devices, like the Garmin Explorer Plus, one could set the active listening interval.

In more recent devices, like the Garmin 66i, the listening intervals are fixed. The trend is clearly towards more controlled active listening. This may be to offset the power consumption of more modern displays and other functionality.,

I am not 100% sure if the delorme use passive listening, will check it, I am admin of a bigger enterprise acc full of delorme devices.

What I know there, I can set the active mail check to almost any time interval. Well the bill is paid by byte  there.

This is one of features we are happy about so far. But also other delorme functions are important for us, garmin was not able to offer us any kind of replacement so far, so will will keep going with delorme.

The matter about power and running receiver all time is clear. But as far as I remember the original iridium pagers, they were operating so far I remember from 2 AA cells for far more then a months at 7/24. Capable to receive msg at any point of the world with no restrictions, no need of declare specific area in advance. OK, the display was dark when not in use, but the rest did work. Often also inside buildings as it uses very slow, thus narrow band communication which is far more superior to the otherwise used burst data.

I do not know how the current new pagers work really, but from power point of view, keeping just the receiver on listening for narrow band call might be not worse then active polling of msg from the server.

If someone ultimately wants know where the particular user is for whom msg is waiting, narrow band listening might be same or better from power consumption view.

I have zero experience in this area...I'm just guessing.

I think 10 minutes of passive listening almost certainly takes less power than 10 minutes of active mail check.

But maybe a single active mail check per hour takes less power than a full hour of passive listening?

And maybe during conditions where there is not a good clear view of sky, the active mail check keeps attempting to make contact and eventually alerts user that there is no clear view of sky, but passive reception does not offer similar level of user feedback.

When DeLorme owned the devices, there WAS (originally) a passive listening mode. Each device listened (briefly) passively every 20 minutes (3 times an hour). I don't remember exactly how things were coordinated, but the combination of the servers and the Iridium network synchronized the "ring" for each device so that it was sent when the device was listening. This worked, but was fragile and complicated. Probably did not scale well to large numbers of devices.

Fast forward to now. The devices probably still passively listen at least occasionally, The ability to control the interval originally varied by device. You used to be able to control it on legacy devices like the Explorer+. I have no idea if that is still true. What IS true is that the message waiting "ring", if it is sent at all, is now broadcast entirely at random. The chances of a passive listen actually "hearing" a ring are virtually zero.

Both passive listen and an active mail check require that the iR modem be powered. An active check does require more power because it involves powering the transmitter to send. Whereas passive listen requires only the receiver. That said, I am sure that powering the receiver continuously would be a significant battery suck.

To be clear, the active check that goes along with (successfully) sending a message or track point is "free" from a power perspective unless there is actually a message waiting. Every transmission expects a positive acknowledgement from the Iridium network. If the device does not get the acknowledgement, it retries the send (at intervals) until it gets one. The "message waiting" flag piggy-backs on the acknowledgement. If the flag says there is a message waiting, then the device asks the network to send it.

An active mail check sends a request to the network to check for pending messages. If there are messages, the device receives them in the normal manner. If not, the device does not expend any additional power (beyond the active check). Whether there is a message or not, the active check waits for an acknowledgement from the network (just like any other "send"). If it does not receive one, it retries (at intervals) until it gets one. This retry is the biggest "surprise" to people who don't know how the process works. If you bury the device in your pack with the power on,. sooner or later it will attempt an active mail check. Battery goes downhill rapidly from there.

I don't know anything about the iR pager or telephone functionality. inReach devices use the "short message service", which is a low(er) cost service. This is what constrains the device messaging protocols.

Very informative twolpert, thanks.

Yes, in the delorme explorer (have one in my hand here) there are settings like 'adaptive check' this is probably supposed to do what todays devices do, namely mailcheck with every transmission. It should also listen for longer time after a message was sent, well this could be passive listen?

I can otherwise set 'Listen interval' to 2min - 20min and also continuous with a warning that this might take lot of power.

There is no clear differentiation between listen and check, as both expressions are used mixed in all menus. There is even an extra page where one should be able to view when the next check will be done and when the last check was done etc. However I know from experience, that viewing this page will show all the time counters, but any mail check will not take place as long this page is in view. (also delorme have bugs)

Anyway, setting it to continuous, it seems to receive a message from the web portal between 1-5 mins.

Setting it 2min does the same.

In our field operations, we have set it to 10min, but we also transmit at 10min, so it does not matter and 'adaptive' is on.

Not really sure if passive 'ring' delivery is really used here, will have to check for transmissions with a receiver one day.

None of the manuals I have does say any details.

The longer listen after a message transmission is standard for all current iR devices. The intent here is to make a message exchange more conversational. These are periodic active listens during the extended conversational interval. Without these active listens, you would need see a reply to your message until the next automatic active listen (average 30 minutes, worst case 1 hour). Even if the recipient of your message sent the reply immediately.

I don't know the exact mechanics here (repeated active checks with no retry; one active check with a restricted retry interval; something else?). But they ARE active checks, not passive listens.

The terminology confusion in the device UI (listen vs. check) is typical. It got WORSE with later devices. 

I doubt that "continuous" really applies to active checks, although anything is possible. I THINK this would mean "continuous passive listen" - meaning that the receiver is on all the time. That would work - you would see every "ring" directed to your device. But it sucks battery. Listening any less frequently than "continuous" runs the risk of missing rings. 

Finally, I am not even sure that the "rings" still exist. That's terminology left over from the early DeLorme days when devices and rings where synchronized at the 20-minute device-specific time hacks. Even if rings are still sent, passive listen rarely if ever detects a message. Better to just use active checks and be done with it.