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Reports are emerging that some cellphones of passengers on the missing Malaysia Airlines Flight MH370 are ringing — but no one picks up. However eerie this seems, it may have more to do with how mobile phones and networks operate than any deeper mystery.
According to a China.org.cn report, 19 families signed a statement saying that dialing their loved ones' phones leads to a ring, rather than going straight to voicemail, as one would expect of a phone in airplane mode or otherwise unable to be reached.
But it's not that simple. When you hit the call button on some phones, a ringing tone begins immediately.
"However, that does not mean the phone you are calling is ringing yet," wrote wireless analyst Jeff Kagan in an email to NBC News. "The network is searching for the phone. First based on where it last was, then it expands. Then if the network can't find the phone, the call terminates."
The search for the party on the receiving end may be nearly instantaneous, or take a few seconds — during which time the phone (depending on model, network and other variables) may or may not make a ringing noise to indicate to the caller that it is attempting to make the cell connection. So while it may ring four times for you, the person you're calling may only hear it ring once -- or not at all.
If the phone you're calling is in airplane mode, or is off, out of range, or destroyed, the network may still take a few seconds to confirm it's unreachable.
In a video from a Chinese news channel purporting to show one of the calls in question, the caller's phone appears to ring for only a second or so before failing. The family members who were able to "get through" or "connect" to a missing person's phone, which subsequently "hung up," could very possibly be experiencing this caller-side ringing effect, Kagan said.
NBCNews.com's Julianne Pepitone contributed to this report.