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Comment by digitalengineer | Hacker News Reader

So we have a plane that flew to another destination without communication and several people with bogus passports on board. Familymembers have reported cellphones that kept 'rining' instead of going directly to voicemail (as they would have if the plane was at rhe bottom of the ocean). Hijacking looks to me the only reasonable explenation.

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This statement has to die. It has been confirmed over and over again that the phones aren't on and this is a network thing. Do you really think that if this plane was hijacked the phones would be kept on especially in light of the Snowden/NSA leaks? Tracking cell phones has been common for over a decade now, I'm sure a hijacker would be aware of this and would toss the cell phones into the ocean.

Like in opening the door at flight level 295 and throwing out a bag full of mobile phones?

It's possible in some cases for phones to "ring" even if they're off/disconnected, as the tone is generated by the network, not the device itself.

In my experience the network won't ring if it hasn't seen the device in a certain time period. "Straight to voicemail" for that. I'm no expert though, maybe rings are still possible.

But if the network is seeing these phones, it seems to me it'd be pretty simple locate these people by just querying the provider for the tower location. This hasn't happened, so the only conclusion is all the phones were destroyed, disabled, or out of range.

>In my experience the network won't ring if it hasn't seen the device in a certain time period. "Straight to voicemail" for that. I'm no expert though, maybe rings are still possible.

You are correct, rings are still possible regardless of the state of the phone connection.

Multiple people who know what they're talking about have confirmed that you don't get the "straight to voicemail" behavior if the phone was last registered on a roaming network rather than its home network. As would be the case for e.g. every single Chinese cell phone that was last turned on in Malaysia.

Is there is some sort of timeout after which it gives up, or a reliable upper bound on the time it takes for a network search, and if so, do you know how long either of those two periods are?

I presume that if you ring a phone, a search is initiated, which would result either the phone being located or the phone being marked as unavailable, and that once the latter had happened you wouldn't get the ringing tone until the phone re-registered on the network.

I only ask because, from memory, the reports that I saw seemed to suggest that people got ringing tones for quite a while, and a cursory search just now indicates phones are still ringing days after the disappearance.

If that was so (unverified assumption), wouldn't that suggest that the network search hadn't yet failed to locate those phones, and that after some period of time that amounts to pretty good evidence that the phones were still connected?

After some link following to [0] I saw tweet [1], which suggests that the phones wouldn't have been on the network at all. It doesn't really answer my questions, but I think it rules out the phones as a source of information.

That tweet implies that the first order answer to my question 'how long before a search times out' is 'a long time'.

[0] http://mh370lost.tumblr.com/ [1] https://twitter.com/AeroMobile/status/443419690350960640

I don't know how networks work in your country or where this accident occured, but in Japan when your phone is off, and you try to call it, it does not ring and indeed goes to voicemail directly.

Instead of turning your phone off, so that it can inform the network that it is going off line, try pulling the battery without warning.

If I turn off my phone gracefully, the network will send incoming calls pretty much straight to voicemail. If my phones battery has died, or the phone dropped off the network for another reason (went camping?), then the network will have your phone ring as it searches for the phone.

No, you will not hear a ringing. The ringing only starts after the phone you are calling has been contacted. When you pull the battery out, the network will keep on searching for your phone and since no phone replies, it will inform you that the phone is out of coverage area.

In my experience cellular phone networks behave very differently in different countries.

In some places I have made calls where I first hear one kind of ring which is then replaced by a second, different kind of ring. A hypothesis is that one network has played a ring tone while it connects to another network, and that the second network plays the other ring tone as the actual phone is ringing. I have even heard three different kinds of tones when making calls to phones that are roaming in foreign countries.

The global phone network is an incredibly heterogeneous spaghetti of different networks built with different gear installed at different times. The internet looks positively homogenous by comparison.

My point is that you shouldn't rush to positively say "No, you will not hear a ringing."

In my experience on US networks, the ring that you hear is completely artificial and the network will have it start before the phone is actually found. That's how you can get a minute or so of ringing followed by the "cannot be found" message.

Seriously, what is the thesis here, that the phones are still 1) intact, 2) charged, 3) on the network, 4) cannot or are not answered, 5) cannot be located? How would those things even make sense, several days after the planes disappearance? That plane sure as shit isn't still flying...

People are identifying something that they consider weird (phones of people on a lost plane ringing) and are using it to justify their pet theories on what happened (involving the phones actually legitimately ringing), without explaining why their pet theory makes anything less weird.

Interesting, I will give it a try.

Article: http://the-tap.blogspot.com/2014/03/mh370-passengers-phones-...

Annnd, why aren't we reading about cell logs of every IMSI of every passenger on board. Isn't this baby stuff? Continually ringing doesn't mean the phone is still on a network.

Continuously ringing means the network still thinks the phone's on the network. When you power down your phone it sends a signal to the network saying it's going off. If you just pull the battery or something else where it doesn't send that signal, the network still assumes (maybe only for a time) that the phone is still on but isn't connected to a tower.

But the ringing only starts once the target phone responds to the paging from network, otherwise the network just keeps on searching and after a timeout informs that the target phone is unreachable or out of coverage area.

That's not true. There are cases (e.g. if the phone was last registered on an overseas network because the person was traveling internationally) where the network will generate a "ring" while still searching for the phone.

Because the "cell" is the microcell generated by the plane's internal GSM/sat uplink... which has no GPS attached and cannot really be traced.

Even if there is no GPS, it should still be possible to tell whether a number is registered/active on the network. When a phone connects to a network (including roaming) it's location is stored in the operator's HLR (home location register) where it is used to route calls. I'd assume it stores the time the phone was last seen as well.

So after 5 days, the hijackers are allowing all the hostages to charge their phones?

I don't think this is remotely plausible, but remember that dumbphones can last well over a week between charges.

Or smartphones too for that matter if you have data turned off (which you would if you were, say, one of 200 Chinese tourists who had just been in Malaysia for vacation)

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