Mobile ID: IMEI, you know?

Probably in the mobile communication of the professional vocabulary is the most familiar with the IMEI, whether in the purchase of a new machine or in the 2-hand market "Gold Rush" when the first action is to check whether the IMEI and fuselage on the motherboard of the IMEI is consistent as the main means to identify authenticity. This article on the IMEI of some of the ins and outs and recognition techniques to do a little bit of a brief introduction hope can help you a little.

FTA Test

When it comes to FTA testing everyone will feel very strange, it seems that there is no connection with the phone IMEI, in fact, all mobile phone manufacturers in order to make their own mobile phones can enter the market, must be to obtain international mobile device identification (and this logo is unique in the global scope) is familiar with the IMEI ( International Mobile Equipment Identifier). The phone without the IMEI will not be available in the GSM network. This IMEI is issued by GSM MOU (that is, GSM Alliance, which includes GSM operator and the manufacturer of GSM mobile phone) organization authorized neutral issuing agency-European Equipment type Certification Center According to the FTA Certification Laboratory test report. To obtain the IMEI number, you must pass the certification test of the FTA Certification laboratory.

The FTA test full name is comprehensive type certification (APPROVAL). The test is based on a specific mobile station conformance test specification in the GSM series standard developed by the European Telecommunication Standards Board (ETSI). The purpose of the test is to check whether the mobile phone meets the requirements of GSM standard. This standard has a total of 1500 pages, depending on the different features supported by the phone, 300 to 500 rigorous tests are required, and the test content is divided into software testing, hardware testing and EMC testing. Through the FTA Test mobile phone is considered to meet the requirements of the GSM protocol, with the ability to carry out practical applications, to be able to apply for and obtain the IMEI and can be used as commodity production. At the same time, for the manufacturers, also proved that their research and development capabilities to achieve a certain level. Therefore, the TFA test is an important job for handset manufacturers. In the domestic mobile phone in the southern high-tech is our country's first to obtain a FTA certification of mobile phone manufacturers.

2001 years after the FTA by the mandatory third-party comprehensive model certification into the authorized testing institutions or manufacturers according to the GSM Accreditation Forum standards and rules for final conformance testing, by the manufacturer for conformance testing conformity statement and product quality overall responsibility.

Due to the implementation of the GSM terminal into the network license system, the application of GSM terminals into the network in line with the national Industrial policy, technical standards, with a sound quality assurance system and after-sales service, but also to provide effective final conformance test report and approved IMEI number. Therefore, in this sense, the FTA certification is necessary, no certification will not be able to obtain the IMEI without these two procedures will not be able to obtain in our country's access to the network license, no net license of course is the unknown of the parallel.

IMEI composition

The IMEI commonly known as "serial number" is stored in the handset's EEPROM (commonly known as the Code slice), each mobile device corresponds to a unique IMEI. Its constituent structure is the TAC (6-digit) +FAC (two-digit) +snr (6-digit) +SP (1-bit number). TAC (device model approval number), assigned by the European Type Certification Center. Familiarity and understanding of this number will play a big role in our future identification of mobile phones. The first three bits of the TAC code are changed at different times, and the previous three bits of the TAC code will not appear on the current phone. In the past, some of the old models of mobile phones are basically 446/448 beginning, such as Moto v328 Nokia 7110, and even if the same phone in different times there will be different TAC code as you are most familiar with the 8210 upgrade 8250, if the first three bits is 448902 can not upgrade, Because the CPU is different. So in the past, as long as the same model of the mobile phone TAC code must be the same argument is not accurate, and then Ericsson's same model mobile phone T39MC in different regions will also have different numbers mainland licensed for 520406 Hong Kong is 520407. We know that these differences can be done through the TAC Code "device recognition", without having to bother to remember the IMEI of the 7.8-digit representative of the origin.

In addition, if the same model of the phone's TAC code at least indicates that the machine has different hardware, such as NOKIA8210, the old version of the CPU 8210 of the TAC code is 448902, and generally able to write 8250 software version of the TAC code is 350 beginning. In fact, the first three of the TAC code represents more of the mobile phone FTA after the allocation of the IMEI time, the real device model identification or the latter three. In the 2 lot market JS is usually replaced with T20 motherboard T29 Shell T29 sold, but T20TAC code for 520259 real T29SC is 520341, so when you get such a phone, you only need to see the IMEI of the TAC will be able to clear the chest, But this does not mean that the imei7,8 bit does not work, and FAC (factory assembly code) is coded by the manufacturer, usually representing the manufacturer and its assembly site. This is also the number that we are most concerned about in the past, because generally as the identification of the origin of the number, it can be very effective to help users identify the source and authenticity of the phone. For example, Nokia's 40/60 earth people know that the representative of the origin of Beijing and Dongguan, as long as the two numbers are not regarded as parallel imports. And if we combine TAC to further understand the real identity of the machine, for example, said T20/t29, we know T29 is Ericsson in Beijing production and T20 is produced in Nanjing, then if a T29 IMEI is 520259-63 ... Oh ~ ~ So must be a fake.

Sometimes FAC can not fully prove whether the handset is licensed, T68 after the sale of hot buy once caused the shortage, so Ericsson agents mobilized a part of Malaysia production (FAC code 71) emergency rescue, so this part of the network license T68 is also "licensed." (We talked about the IMEI and the connection between the Access network license) However, it should be noted that this part of the T68 is limited to the T68 of the earlier part of the software version R1b.

The FAC code is not immutable even for products of the same origin, such as Siemens 3508I and Moto C300 because of its huge production has been upgraded from the beginning of 37 to 40, while C300 's licensed FAC also has 80/81/82. Of particular importance is the European model Certification Center this year redistributed IMEI,FAC was merged with the TAC, the number of the FAC is unified starting from 00, so no matter what model what brand its 7, 8 bits are 00, such as the latest C289, Samsung V200, Siemens A55, Sony Ericsson T618 all appear on the handset 351***00 such IMEI. Fortunately we have previously introduced the TAC code identification method, such as the T618 IMEI although the past FAC now unified 00 but Hong Kong and the mainland licensed TAC after the three-bit is still different. Hong Kong behavior 351253 mainland T618 351254, in fact, here has been explained that a problem 351253 represents T610 (Chinese Traditional version) 351254 is T618. and the real meaning of the TAC code is here-the device type approval.

Now it's time to say the SNR code. The SNR Code order number is also assigned by the manufacturer. Identify one of the devices in each TAC and FAC. The SNR of each cell phone is not the same. Simply say that the number of mobile phone production date of the order, usually the larger the number indicates that the later the factory time, so if a newly listed mobile phone IMEI appeared on the 6-digit number you have to be careful, because the newly listed mobile phone its SNR is not more than four, we can buy the machine to pay attention to a bit. Perhaps this can be used as a way to identify whether the phone is JS modified IMEI.

SP Backup code, as the name implies to do backup, about SP only a little need to explain that the SP is basically no as the previous article said that "generally 0", its number is set by the manufacturer, can be ignored.

Of course, some phones make their own definitions on the IMEI. Ericsson Phone Input * #06 # on standby will appear 17-bit IMEI, the last two bits of the main role is to identify the software version. It should be explained here that Samsung V200 also started using the 17-bit IMEI, the last two bits of the main function is to identify the software version, in general, the lower the value of the lower version, such as T618 R1a version of 02 and r1f version is 03, the latest r1l version is 05.

As we have said before, each mobile device has a device identification number (IMEI), mobile devices such as the permitted access to the operating network, must be approved by the European Model Certification Center, and assigned to a decimal 6 digits, occupy IMEI15 decimal digits of the first 6 digits. In fact, the role of device identification is to ensure that the mobile device used in the system is not stolen or illegal. The identification of the device is done in a eir called device recognition Register, and the IMEI is stored in the EIR. There are three lists in Eir: The whitelist---includes all the device identification sequence numbers that have been assigned to the GSM countries that can participate in the operation. The blacklist---includes all device identifiers that should be disabled. The grey list---includes faulty and non-model-certified mobile devices, which are determined by the network operator.

Below we briefly introduce the device recognition program in mobile communication, the mobile phone user initiates the call, the Mobile Switching Center (MSC) and the call location Register (VLR) requests the IMEI to the mobile station (mobile phone), and sends it to the Eir,eir will receive the IMEI with white, black, gray three kinds of table to compare, Send the results to MSC/VLR so that MSC/VLR decides whether to allow the mobile device to enter the network. So if the mobile station is using a stolen mobile phone or a faulty non-model-certified mobile device, then MSC/VLR will determine the location of the stolen mobile station and block it, the fault of the mobile station can also take timely preventive measures. What we usually call tracking a stolen phone through a web tracker is achieved through EIR. Currently, network operators such as Vodafone have begun using the business to monitor stolen handsets. Unfortunately, our country basically did not use EIR to identify the IMEI, and if the stolen phone to replace the network and modify the IMEI so Eir will be powerless.

In fact, as a mobile phone "id" of the IMEI has some other uses, such as Samsung's Samsung Park registration if not the regular channel access to the phone will not be able to enjoy the registration of the service, also for Sony Ericsson mobile phone users, IMEI can also be in the manufacturers of some websites through the IMEI register to enjoy free pictures, ringtones, painted screen download, and even the IMEI will be as the user's maintenance upgrade according to record in the Customer service center. Therefore, in this sense, the IMEI will play a more and more important role in the future mobile communication.