Emergency calls certainly work without one, so basic communication (probably enough for this use) is possible.
huh my former field here :)
years ago I worked for T-Mobile and was drafted to Siemens where I was responsible for getting BTS (that thing with antennas) and BSS (next box in line) so I can provide shitload of boring info but basically this is true.
but don’t forget how was GPS designed, where it works perfectly and where not, and what it means for simple GPS altitude accuracy (without WAAS/EGNOS etc).
Peter wrote:
For sure a SIM card is not required for the GPS in an Ipad to “work”, but the Q is whether “GSM-assisted” GPS works without a SIM card. I don’t think you get any GSM tower comms without a SIM card, but could well be wrong.
So the iPad Mini 4 I’ve tried out doesn’t have a SIM card installed. When I first turned it on it did have a WiFi connection. It had at one point been turned off for about 24 hours and simultaneously moved some 30 km. When I subsequently turned it on (now without any WiFi connection) I got a GPS fix almost instantaneously.
If the A-GPS service is in the mobile network itself, it could conceivably work without a SIM card — just like you can make emergency calls without a SIM card.
Next time I’ll put it in flight mode before turning it off to see what happens with the GPS.
The new iOS 11 menu, it seems, has changed the settings compared to iOS 10… Before, when I put the pad into flight mode and i.e. activated skydemon, close to the window of an airliner, and go on “fly”, you would get a GPS location after a couple of seconds. Meaning, the GPS would work without Wifi or cellular net activated.
When I put my iPad 4 (which has a SIM card) into flight mode under iOS 11, I don’t seem to get a GPS fix unless I also activate the little antenna symbol right beside the flight mode symbol. Unfortunately, this also turns the cell network on. Which is bad for various reasons: 1, I’ll get the continues zzzz zzzz zzzz sound into my headphone, and 2 it’s useless above 5000ft and 3 it draws a lot of energy. Not good.
have to edit myself, it was end of nineties when I went of this field and A-GPS was in draft back then. So I did some search in specifications and apparently there is not much you can get from assisted GPS without network, specially without internet data. All you can get, and it depends on provider setup, is satellite almanac so regular GPS is a bit quicker when acquiring position but there is no benefit from A-GPS accuracy any other functions as these are mainly done at provider agps server and results sent back to phone.
As the almanac is cached anyway so it is easy to predict next satellites for same area you will not see any significant difference unless you do a flight to asia for example and turn it on without data or gsm network. First fix can take and will probably take over 30 seconds which is something I can confirm as this is usually happening to me when I have GSM off at these places (due to insane roaming prices like 15EUR per megabyte)
When I put my iPad 4 (which has a SIM card) into flight mode under iOS 11, I don’t seem to get a GPS fix unless I also activate the little antenna symbol right beside the flight mode symbol. Unfortunately, this also turns the cell network on
IMHO this is way too big to be a bug. It must be Apple’s way of harvesting data, probably passively collected wifi data like Samsung appears to be doing. I can see Samsung (android) having access to all the wifi location data which google collected with their street surveying cars, but obviously google aren’t going to give Apple access to that 
So Apple have to compile their own database. Getting this wifi data sent back to the church HQ via GSM (mobile internet) is becoming increasingly important as free wifi becomes increasingly rare… vanishingly rare in actual use since having a decent mobile data allowance is standard and is infinitely easier to use when sitting in a cafe than bothering the waitress for the wifi password and whether it is case sensitive (a phrase she may not understand). Even in hotels it often doesn’t work because of some issue (one awfully pricey ski resort hotel I recall disconnected you for a few seconds every 10 minutes, presumably to break go-pro 4K video uploads
).
All you can get, and it depends on provider setup, is satellite almanac
@pimparoo do you mean that the phone can get the almanac over GSM, from the GSM network itself?
If the phone calls up the network company holding the phone account, or say google in the case of an android phone, it can get whatever it likes, and fairly obviously wifi location assistance has to be over mobile data because the worldwide wifi AP location database cannot possibly be stored in the phone. It needs only GPRS however.
I am using 11.2.2 iOs on my iPad Air 2, iPad Pro 9.7, and iPhone 6+, sitting in my office on the first floor of my home with wifi, BT, and antenna turned off. I still get good GPS reception, 10 M or better, and the three devices agree within +/- 1 foot with the GPS altitude. The iPad Pro is equipped for cellular, but there is no cellular service. The others are equipped for cellular service, but I have turned off the antenna icon so are not currently connected to my carrier.
EuroFlyer wrote:
When I put my iPad 4 (which has a SIM card) into flight mode under iOS 11, I don’t seem to get a GPS fix unless I also activate the little antenna symbol right beside the flight mode symbol. Unfortunately, this also turns the cell network on.
Another data point: Yesterday I turned the iPad Mini 4 off while in flight mode (with no antenna symbol activated). After some 20 hours, the tablet was moved 15 km and turned on. Again, as soon as I had started Garnin Pilot and selected the map, I had a GPS fix at the correct location.
This iPad Mini also uses iOS 11.
