Mobile without valid IMEI Number are a threat to National Security

Mobile phones have grown to be indispensable to our life. It has done wonders to stay us connected 24×7. India is being recognized as the fastest growing mobile phone market in the world. However, the same mobile phones may also sometime pose a threat to national security. It is estimated that there are around 30 million Chinese handsets[i] in the country which lack an International Mobile Equipment Identity (IMEI) number which poses a serious threats to the national security as such phones have allegedly been used by the terrorists. The telecom ministry also estimates that around 30 million or eight percent of India’s mobile phone subscribers use the cheap handsets without IMEI number that are generally imported from China and Taiwan.

The Chinese handsets without a valid IMEI number were hitherto (before ban) available very easily in Grey Indian Market and one can buy such Chinese handset mostly imitation of popular costly mobile brands like Nokia N 97 being sold like hotcakes as the customers from lower income groups can purchase it at cheaper rates offering them the same features as that of the costly original version. However, without valid IMEI number, as stated aforesaid the customers were using such sets at the cost of national security.

So what is an IMEI Number[ii]?

IMEI is known as International Mobile Equipment Identity. The IMEI is a 15 digit number which includes information on the origin, model, and serial number of the device. It helps in uniquely identifying a handset and its location on the network and most importantly allows security agencies to track down a specific user. It can be displayed on most phones by dialing *#06#. It is also usually printed on the compliance plate under the battery. The numerical format of IMEI currently utilized is:-


It should be noted that no two mobile handsets in the world should have the same IMEI number. With the IMEI number, the GSM operators can locate, track or immobilize a handset. Whenever a user makes a call from his handset IMEI number on genuine handsets gets reflected at the operator’s network thus enabling identification of the caller or lawful interception of all calls and it also allow the investigating agencies to trace various mobile number used on the same mobile instruments. With the IMEI number in hand and working in collaboration with the telecom operators, it becomes very easy for the investigating agencies to detect the location or user of the subject mobile number. It was on the basis of the IMEI number that the police established that LeT operative David Coleman Headley had stayed in Lemon Tree Hotel in Mithakali, before 26/11 attacks[iii]. Further, recently in the Mumbai Terror attacks, the investigation into some of the mobile numbers used by the deceased terrorists of the Mumbai terror attacks revealed the Pakistani connection. The terrorists in the course of offence used five mobile handsets for communicating/seeking instructions from the co-conspirators in Pakistan. The investigation into the IMEI numbers of these handsets has revealed that these were manufactured at the Nokia factory, at Dong Guan, China and shipped to Pakistan[iv]. The details are as per overleaf:

S. No. Details of mobile

Place of offence

Details of vendor

1. Nokia 1200, IMEI No. 353526024049451

Hotel Taj

United Mobile, Pakistan

2. Nokia 1200, IMEI No. 353526025840890

Hotel Taj

12 Pakistan (Pvt) Ltd

3. Nokia 1200, IMEI No. 353526025828739

Nariman House

12 Pakistan (Pvt) Ltd

4. Nokia 1200, IMEI No. 353526025842235

Nariman House

12 Pakistan (Pvt) Ltd

5. Nokia 1200, IMEI No. 353526025933620

Hotel Oberoi

United Mobiles, Pakistan

It is further revealed that the address of 12 Pakistan (Pvt) Ltd is, 2nd Typical Floor, Executive Tower, Dolmen City, Block 4, Clifton, Karachi, Pakistan.

The importance of IMEI number from the security point of view cannot be overlooked as investigators investigating the various terrorist attacks in our country have reported that some of the terrorists were using Chinese mobile phones in which the International Mobile Equipment Identity (IMEI) number, or a 15-digit code that appears on the operator’s network whenever a call is made, is absent. The intelligence agencies warned that in the past too, terrorists have been found using Chinese phones, in which the code is absent, to carry out attacks in the country. The absence of this IMEI number literally makes the work of the investigating agencies impossible to trace the culprit and connect him with crime particularly when the culprit replaces his existing SIM card with a new SIM card in his mobile phone without a valid IMEI number. However, it is to be noted that though by dialing *#16# one can see IMEI number being displayed on the screen, however, the mobile call records reveal only first 14 digit out of 15 digit and the last digit is always missing which is known as Check Digit. The investigating agencies, obviously match the 14 digit IMEI number i.e. made available by the mobile service provider companies with the subject mobile. The defense often raises question/objection with respect to the missing last 15 digit known as “Check Digit”. Generally, the controversy pertains to the last digit recorded in the seizure memo prepared by the investigating agencies when the handset is recovered and the last digit recorded in the call details provided by the service provider. The same question arose before the Supreme Court, in the decision reported as State (NCT of Delhi) v. Navjot Sandhu, AIR2005SC3820 , the Supreme Court dealt with the said issue as under:

One more point has to be clarified. In the seizure memo (Ext. 61/4), the IMEI number of Nokia phone found in the truck was noted as …52432. That means the last digit ‘2’ varies from the call records wherein it was noted as …52430. Thus, there is a seeming discrepancy as far as the last digit is concerned. This discrepancy stands explained by the evidence of PW 78 – a computer Engineer working as Manager, Siemens. He stated, while giving various details of the 15 digits, that the last one digit is a spare digit and the last digit, according to GSM specification should be transmitted by the mobile phone as ‘0’….

How to check the “Check Digit”?

To understand the calculation of “Check Digit”, first let’s see at the structure of the IMEI itself:

  1. The origin and model comprise the initial 8-digit portion of the IMEI, known as the Type Allocation Code (TAC).
  2. The first two digits of TAC are for the Reporting Body Identifier and indicate the GSMA-approved organization that registered a given mobile device, and allocated the model a unique code.
  3. The remainder of the IMEI is manufacturer-defined serial no. which has been uniquely assigned to the specific type of handset.
  4. The CD (Check Digit) is used to check the code for its validity (which is never transmitted) for Phase 2 and Phase 2+ handsets. Phase 1 GSM handsets, however, always have zero (“0”) as check digit.

Check Digit:

  1. The last number of the IMEI is a check digit calculated using the Luhn algorithm.
  2. The check digit shall always be transmitted to the network as “0”
  3. The purpose of the Check Digit is to help guard against the possibility of incorrect entries to the CEIR and EIR equipment.
  4. The Software Version Number (SVN) of a mobile is not included in the calculation

“Computation of Check Digit”

The check digit is validated in three steps:

  1. Starting from the right, double a digit every 2 digits (e.g. 7 → 14)
  2. Sum the digits (e.g. 14 → 1 + 4)
  3. Check if the sum is divisible by 10

Conversely, one can calculate the IMEI by choosing the check digit which would give a sum divisible by 10. For the example IMEI 49015420323751?

IMEI 4 9 0 1 5 4 2 0 3 2 3 7 5 1 ?
Double every other 4 18 0 2 5 8 2 0 3 4 3 14 5 2 ?
Sum digits 4 + (1 + 8 ) + 0 + 2 + 5 + 8 + 2 + 0 + 3 + 4 + 3 + (1 + 4) + 5 + 2 + ? = 52 + ?

To make the sum divisible by 10, we set ? = 8, so the IMEI is 490154203237518

This is how the investigating agencies calculate the missing 15th digit which is also known as Check Digit”.

Evidentiary value of IMEI number: In the number of the cases, conviction has been done on the basis of the mobile record and analysis of the IMEI number found on the mobile which has been well settled in the famous Parliament Attack Case stated supra. Further, in a recent case decided by the Hon’ble Delhi High Court in Gajraj V. State decided on 18.03.2009 (Crl. A. No. 461/2008) reveals that the crucial evidence relating to the subject mobile phone having IMEI No. 35136304044030 was considered. In this case the most important piece of evidence brought on record by the prosecution to connect the accused with the commission of the crime was that the handset having IEMI No. 35136304044030 was being used by the deceased just before his death as evidenced from the call record and the said handset was in the possession of the accused soon after the death of the deceased, inasmuch as, call record evidenced that the mobile number 9818480558, which number was registered in the name of the accused, was being used in the said handset with effect from 24.07.2005; the factum of the possession of the said handset by the accused is further reinforced by the fact that the said handset was recovered from his house at the instance of the accused. Thus, independent of the physical recovery of the handset at the instance of the accused, through the medium of the call details of deceased and accused, there is unimpeachable evidence that the mobile phone of the deceased came in possession of the accused/appellant within 19 hours of the death of the deceased. Similarly, in another case of Vinod Kumar Vs. State [Crl. A. No. 521/2008] decided on 16.03.2009 (Delhi High Court), reveals that the IMEI number of the mobile phone used by the accused person connected him with the crime of the murder of the deceased.

Mobile Phone without IMEI Numbers banned in the interest of national security

Taking serious note of the situation pertaining to the circulation of mobile phones without IMEI number and its potential threat for the national security in view of recent Mumbai Terror attacks, the Department of Telecommunication, Government of India, vide its Letter No. 20-40/2006-BS-III(Pt.) (Vol. I)/201, dt. 3rd September, 2009 has directed all the Cellular Mobile Service Providers that calls from the mobile handsets with any IMEI number which is not available in the latest updated IMEI database of GSMA[v] along with without IMEI or all zeros as IMEI are also not processed and rejected with effect from 24 hrs of 30th November, 2009.

The government approved earlier this year a Genuine IMEI Implant (GII) proposal from service providers that programs genuine IMEI on mobile handsets. In a letter to service providers in April, the Ministry of Communications & IT recognized that some of the users of phones without proper IMEIs were “genuine innocent subscribers”[vi]. The cellular operators in India in compliance of the DoT communiqué and direction had offered such subscribers without IMEI number to either discard their handsets or bring them to official outlets of cellular companies to re-programme their IMEI numbers. One without valid IMEI number can go to these official outlets and get IMEI reactivated at a nominal charge of Rs 199/- only. The Mobile Standards Alliance of India (MSAI) is exclusively authorized body in India by GSM Association (GSMA) to perform Genuine IMEI Implant program (GII). MSAI is working in partnership with Cellular Operators Association of India (COAI) and Department of Telecommunications (DOT) to implant the genuine IMEI numbers on to the mobile handsets which are carrying bad/non genuine IMEI numbers as a one time Amnesty Program. The subscribers without having any valid IMEI numbers while visiting these GII centre’s (about 1600 such centers) across the country had to carry with a valid identity proof like, PAN CARD, driving license, Voter ID Card, Passport, ration card etc. for identification purposes.

There were significant rush seen at the GII centre’s and some unscrupulous mobile vendors in the Grey market have taken advantage of the situation and claimed that they have the facility to implant valid IMEI number in the mobiles or their mobiles are sold with valid IMEI numbers. The Crime Branch of Delhi Police on the complaint of the Indian Cellular Association have conducted raid on December 9, 2009 at in the Karol Bagh Electronics market and arrested 23 mobile vendors who were found selling banned Chinese mobile phones. The police have seized from them a total of 3,500 mobile handsets without the IMEI numbers. A “Spiderman Software Box” which was imported from China to upload fake IMEI number on handsets has also been seized from these vendors. The implanting of fake IMEI numbers and selling it to innocent customers have very serious ramifications as far as the national security is concerned. Given the large number of banned Chinese mobiles in circulation, it could lead to large scale tampering/manipulation of IMEI numbers. Given the increasing role of cell phone transcripts in monitoring and investigating anti-social activities including high profile terror cases, usage of fake IMEI number could lead to failure of the very objective of the GII drive initiated by the Department of Telecommunications, Government of India.

Earlier, the Mumbai police have also conducted similar raids on October, 2009 and seized banned Chinese mobile phones without IMEI numbers. The offenders were booked under Section 41(d) of the Criminal Procedure Code which empowers the police to arrest any person who is suspected to be in possession of stolen property. However, Section 41 Cr.P.C. is not a penal provision and only empowers the police to arrest a person under certain circumstances mentioned under the said Section 41 Cr.P.C.

However, the implantation of fake IMEI number in the mobile phone attracts the penal provision of Section 420, 468 read with Section 471 Indian Penal Code, as the mobile vendors are cheating the gullible customers by passing them banned mobile phones with fake IMEI numbers as genuine one and part with their hard earned money. Further, they for the purpose of cheating commit forgery of the IMEI number which is an electronic record and thus attracts Section 468 IPC and by showing the mobile having fake IMEI number as genuine one, when they have reasons to believe that the same are forged one, the section 471 IPC is also attracted. The Delhi police have imposed these sections of Indian Penal Code on these unscrupulous vendors of banned Chinese mobile phones which are cognizable and non-bailable and have shown non compromising attitude of the Government of India as far as national security is concerned.

[i] Source: KPMG: Information, Communication and Entertainment -An Inconvenient Reality The unaccounted consequences of non-genuine software usage -Advisory

[ii] For details about IMEI number please visit:

[iii] Source: News article published in Ahmedabad on December, 11, 2009.

[iv] Source:,

[v] GSMA representing the interests of the worldwide mobile communication industry is the only body which supplies the IMEI numbers to Mobile Handset manufacturers worldwide through its reporting bodies and maintains the IMEI database of worldwide genuine IMEI numbers. This IMEI database is also activated and updated every 15 days in the EIR of mobile operator’s network.

[vi] See DoT letter no. 20-40/2006-BS-III (Pt.) (Vol.I)/109 dt. 27th April, 2009


  • Thanks for posting the article, was certainly a great read!

  • HarshaGaurav /

    Hello bhaiya,

    Ur article is really impressive…and very useful…keep it up…


  • Sir i am from India using New Company Mobile: LAVA A9. This company newly launched in India, I can’t check his IMEI Code. Please give me suggestion about how to check mobile phone IMEI Code, especially Indian Mobile Phone. I am waiting for reply…

  • We have been doing research on recording mobile phone calls that come into my cell phone and I live in a one party concent state. I’ve tried those recorders that connect to your phone without success. Thank you for your infomative blog, it was very helpful

  • I found your blog using Google and I must say this is one of the most informative blogs I have read in a while. I will make sure I come back to read your future posts.

  • Sir


    mera naam vimal gupta hai or main India , Punjab, Ludhiana se hu.

    main aap se puchna chata hu ke kya mobile companies or mobile shopkeeper ko IMEI no or us person ka pura record rakhna hota hai jis ko vo mobile ya Internet Dongle sale kar rahey hai.

    kya koi aisa Law hai jis main shopkeeper ko customer ka record rakhna ho ya Bill book pe us ka naam address or phone no likna hota ho

    main aap ke jawaw ka wait karo ga sir

    thank you


    vimal gupta

    • As per guidelines of the Govt., all the mobile companies are reqd. to keep the information of the subscriber along with their identity proof and their photographs.

  • hi sir,
    two handset have same imei no any problem that mobile

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