NavList:

David you wrote:
"Can you get a GNSS and mobile phone signal inside an enclosed steel shipping container?"

Heh. Yeah. That's a problem! Well, let's assume the container was open a bit (they have to breathe after all). Then a phone signal would be relatively easy. GPS/GNSS? No. But smartphones are smart. The "location services" function in nearly all smart devices can often get an excellent fix in an urban/industrial setting even if there's no satellite signal. The simplest technique "triangulates" from the signal strength of nearby WiFi hotspots. Would that work in a container yard? Most likely, yes, since (at least some) container yards have installed large numbers of hotspots for this exact purpose. Then all you have to do is share your location using an almost endless supply of app options or (if you're chatting on the phone) read out your lat/lon from numerous options.

Frank Reed