Mobile phone "hidden function" Secrets

 

Articles on the "Mobile Phone hiding function" on the Internet are widely spread, and the "life-saving phone" can be called without any signal, to the "Hidden battery" that makes the battery instantly Half-Blood revived ", it's no longer a pity to say "drive door", "anti-theft", and "eavesdropping ". These statements seem like true or false. Let's analyze them one by one.

 

Rumor 1: emergency: the common emergency number that mobile phones around the world can call is 112. If you find that your region has no mobile phone signal coverage, and you have encountered an emergency, you can call 112 on your mobile phone, because your mobile phone will automatically search for all available networks and create an emergency call.

Truth:This is not a rumor, but it is useless in China.

"Emergency Call" is a service provided by the GSM network [1] (similar standards are also available in other systems. Here we use the most extensive GSM as an example ), the built-in international emergency numbers include 911 in the United States, 112 in Europe, and 08 in Mexico. The mobile phone directly sends an emergency call instruction to the network for an emergency call, which does not rely on SIM card identification and is therefore not restricted by the operator. If your mobile phone shows that there is no signal because your carrier does not cover this region, and other carriers have networks, it is feasible to make emergency calls. If there is no signal, it will not help.

However, the domestic call 112 does not have a practical effect. It will automatically transfer a voice prompt, "Please dial 110 for the police, please dial 119 for fire alarms ......",. China's emergency numbers such as 110, 119, and 120 still require mobile phone access to the SIM card provider's network, just like normal calls. Although this practice complies with GSM specifications [2], it remains to be improved by domestic service providers in order to better implement emergency rescue.

Conclusion:Although this rumor contains correct information, it has no practical significance in China. If you are in distress abroad, you can try this method for help.

 

Rumor 2: invisible backup battery: Your cell phone is underpowered. to enable it to continue using, press the * 3370 # key and the phone will restart, you will find that the power usage increases by 50%.

Truth:First, we declare that the invisible batteries do not exist in the Three-dimensional world we live in. When you split a mobile phone, you will find that there is no "invisible battery" in it, and the mobile phone manufacturer has no reason to set such a function.

So * 3370 # What is it? If you have tried this command on the old Saipan phone, you will receive the following prompt:

The feedback obtained by entering the command on the old Saipan mobile phone.

When you see this prompt, you should suddenly realize: * 3370 # is the command to enable the "Full Rate Speech Encoding" function in the old Saipan system. What's more hateful is that running * 3370 # Not only does not increase the power consumption, but increases the power consumption.

The voice call function of a mobile phone is to convert the voice signal into a voltage signal first, and then convert the voltage value at each time point into a binary code for transmission. To clearly transmit the original voice signal, at least 128 kbit/s transmission rate is required, which is almost impossible in practical application. Due to the increasing number of mobile phone users, wireless channels become very crowded. To accommodate more users, you must try to compress voice data. However, compression will result in losses. To achieve higher channel utilization, we must sacrifice more speech quality. To ensure high-quality voice calls, we must increase the amount of information transmitted.

This is difficult to perfectly reconcile the contradiction, so two types of GSM speech encoding standards [3] are allowed (in fact there are two improved types and fourteen adaptive encoding rates) prediction encoding technology with different compression ratios is available, that is, Full Rate Speech Encoding (Full Rate Speech encode) and Half Rate Speech Encoding (Half Rate Speech encode ). After full-speed encoding and compression, the data rate is 13 kbit/s, while the data rate is only 5.6 kbit/s after the half-rate encoding and compression. * 3370 # this is exactly the command used to switch to the full rate Speech Encoding mode in the old Saipan system. On the contrary, the command used to disable the full rate encoding mode is #3370 #.

After enabling the full rate Speech Encoding Method, the power consumption increases as the amount of Upstream data increases, which is more powerful than the Half Rate Speech Encoding Method. I was hoping that this method would be a tough option for my classmates? Of course, most mobile phone systems do not have this command, and there are other options for setting clear calls.

Conclusion: rumors are cracked.Input * 3370 # is not a command to enable the invisible battery, but a command to enable "full rate voice encoding", that is, clear call. This command increases the power consumption during a call, it is not suitable for low power usage.

 

Rumor 3: when a car's remote control is located in the car one day and the standby remote control is at home, you will find that there is a mobile phone that is really convenient to use to dial the mobile phone of your family, take your phone 1 feet away from the door, and press the unlock key on the remote control next to your phone with the remote control. This method works no matter how far you drive away from home.

Truth:This rumor is actually a no-justification. A car owner can try to smash it. Here we will analyze the principles.

Currently, most vehicle remote controls use radio control. After pressing the key, the remote control emits specially modulated radio waves. When the receiver in the car receives the radio waves and performs Demodulation to confirm the pairing, the corresponding action is performed. The frequency of electric waves emitted by the remote control is mostly near 315mhz and 433mhz. The frequency of electric waves is higher than that of 2G or 3G mobile phones (for example, GSM mobile phones are 1800 MHz and MHz ), it can be said that the two are "different languages ".

The phone call function is to convert sound signals into electromagnetic signals, and there is no function to design wireless waves that can accept the remote control band and send them to the mobile phone band. Even if the remote control radio waves are doped into the voice analog signal due to the design defect of the mobile phone line, the multi-level filtering process afterwards will be wiped out, not to mention the speech sampling rate (8 kHz) it is impossible to effectively sample and restore such a high frequency signal [4].

Is it possible that the signal from the remote control interferes with the electric wave sent from the mobile phone and is sent to the received mobile phone? This is also impossible. The communication between the mobile phone and the mobile phone must go through the base station-wired exchange network-the base station's transit [5]. The signal received by your mobile phone is not directly sent by the other mobile phone. Even if the remote control causes interference to the phone signal, the first level of the base station will be completely removed.

Conclusion: rumors are cracked.There is no reason for this rumor, and it may be caused by the mechanism of dialing the phone number. You don't have to be lucky. You can take the key with you for a long memory ~~

 

Rumor 4: mobile phones are not afraid of stealing: every mobile phone in the world has a unique serial number, which is recorded and saved. One day, if your mobile phone is stolen, you can call your mobile phone provider and provide your mobile phone serial number. They will shield your mobile phone, even if the thief changes the SIM card, still unable to use, your mobile phone has become useless for thieves. If every mobile phone holder in the world does this, it makes no sense to steal a mobile phone.

Truth:Theoretically, it is possible to disable a mobile phone through device identification. In a GSM network, each mobile device has a device identification code (IMEI) consisting of 15 digits in decimal format [6]. The first six digits of IMEI are used to identify devices, the function of identification is to ensure that the mobile devices used in the system are not stolen or illegal.

Device identification is completed in the device identification register EIR. You can disable the corresponding device by modifying the device identifier in the blacklist of the EIR instance. The EIR device was designed during the design of the GSM network. However, many countries have not installed or activated the EIR device, and related functions cannot be implemented. Currently, China's major mobile communication networks have not enabled this device.

In addition, the IMEI code is not completely reliable. Generally, the IMEI code is stored in the phone's EEPROM (which can be erased by the power of programmable read-only memory) chip, and the content of the chip can be modified. Moreover, non-regular mobile phone manufacturers may not follow the IMEI rules during production, and do not use or use fake IMEI codes (refer to China shanzhai machine identification code storm [7]).

In CDMA systems, similar numbers are called ESN. CDMA operators in China usually do not check the ESN number, and only mobile phones with a foreign host card are used for identification. The 3G system continues the IMEI System of the GSM network.

Conclusion:This rumor is basically true, but the method is not reliable. The machine identification code can be modified at will. At present, Chinese operators have not enabled the identification equipment.

 

Rumor 5: expose your location: even if the phone is turned off, the remote program can activate it and expose your coordinates as long as there is a battery. The solution is to remove the cell phone's battery and completely cut off the power of the phone.

Truth:The rumor was probably influenced by many high-tech action movies. The development of eavesdropping technology has a long history and has been favored by intelligence departments in various countries. The latest technology is hard for most people to understand and makes this rumor hard to prove false. But at least we do not need to worry, because ordinary mobile phones do not have this function.

After our cell phone is shut down, although not all parts are powered off, the main power consumption is codec (audio codecs) the power supply of wireless modules and processors is cut off by the power management chip in the mobile phone and no longer capable of sending and receiving signals. Mobile phone circuits are all open materials. If there are any special functions, there will be traces, and there is no need to worry about hidden xuanjicang. Moreover, mobile phone manufacturers have no reason to design such functions for ordinary people.

Conclusion:Rumors themselves cannot be falsified. It is not ruled out that there is a "technology" that can be used to snoop mobile phones. However, ordinary people do not have to worry that the mobile phones we buy on the market will not be equipped with such "advanced" features. For confidential personnel, follow relevant regulations.

 

 

Remarks: This article Reprinted from: http://www.guokr.com/article/88222/