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Conflict & Tragedy

Family members of Flight 370 passengers able to ring relatives' cellphones

A new twist has been added to the mysterious disappearance of Malaysia Airlines Flight 370 as reports have surfaced that family members of some of the passengers said they have been able to make calls to their loved ones' cellphones, according to the Singapore Strait Times on Tuesday.

According to these reports, the calls appear to be ringing through to the cellphones but no one answers and are then picked up by voicemail. Additionally, there are reports that some of the passengers' social networking accounts are still active as if they are online.

Persistent rumors of contact with phones of those on board the jetliner prompted Malaysia Airlines officials to call the phones of crew members aboard the plane and they also rang through.

According to the report:

Several family members told Mr. Dunleavy that passengers' mobile phones were ringing, although no one picked up.

The connection should be used to get the Global Positioning System coordinates of the phones' locations, they said.

Mr. Dunleavy said MAS was also trying the mobile phones of the crew members, and that they also rang. But it could not do more, he said, and had given the numbers to the Chinese authorities.

At one point, rumors and excitement spread that one passenger had called home, but Mr. Dunleavy said this was likely a hoax.

If these reports are true, this could be very important information that may actually lead to finding the aircraft.

Cellphones operate on technologies that require the use of special equipment to send, receive and route calls.

During calls, the caller phone seeks out and connects to a cell site, colloquially called a cell tower or simply “tower.” The call is routed to what is called a switch. The switch conducts a global scan for the other phone then connects the call via the strongest cell site.

This is important because in order for a phone to receive a call it has to be within range of a cell site. If the phone is out of range or turned off, the call will be diverted to a server that stores voice messages for later retrieval.

Cellphone carriers have the ability to determine whether or not a phone is active on its network. They can also tell what network the phone is operating on even if it is pinging off another carrier's cell sites.

The range of a cell site depends on line-of-sight propagation, frequencies being used, and other variables and can be affected by terrain and atmospheric conditions as well. Unless a device is waterproof, it will cease to function if submerged in water. If calls are actually reaching the phones, this indicates that the devices are functioning and located on land somewhere within range of a cell site.

Carriers can triangulate location based on what cell sites are picking up the signal.

Smartphones also have built-in GPS that can function as long as there is power to the phone.

The ringing callers are experiencing, however, could also be the result of a delayed effect of the networks attempting to reach the other phones.

"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,” Kagan wrote.

Sources and resources:

http://en.wikipedia.org/wiki/Cellular_network

http://www.washingtonpost.com/world/vanished-malaysia-airlines-flight-leaves-relatives-with-anger-and-phantom-phone-calls/2014/03/10/fdb78642-a862-11e3-b61e-8051b8b52d06_story.html