All over the world the most common technology used for the mobile handsets is the GSM technology, because there are the international players like Vodafone, Orange, Airtel, etc spread in many countries and continents and they use the standard SIM cards that work for GSM enabled handsets only. Though not as largely spread as GSM networks, the CDMA networks are also equally popular in countries like India with the players like TATA and Reliance.
Now we need to know two terms – GSM and CDMA.
GSM mobile handsets
GSM is the acronym for Global System for Mobile communications (originally from Groupe Spécial Mobile) and is the most popular standard for mobile phones in the world. The GSM Association acts as the promoter of this network and according to their estimates 80% of the global mobile market uses the GSM standard.
For more technical details, you can perform a Google Search with the terms GSM and you will find loads of information on technical and historical evolution of the mobile networks.
One of the key features of GSM is the SIM card Subscriber Identity Module, commonly known as a SIM card. The SIM card is just like a detachable smart card containing the user's subscription information like the mobile phone number and the address book. By changing the SIM card into a different handset, the user can still use the same mobile phone number and the same service provider.
Similarly the user can also change operators while retaining the handset simply by changing the SIM. Some operators will block this by allowing the phone to use only a single SIM, or only a SIM issued by them. This practice is known as SIM locking although it is illegal in some countries, but this is a part of their offer campaigns and the users can also pay some fee to unlock them.
SIM card is dependent on the Service provider and that is the reason you were obliged to change your mobile number when you used to change your Service provider until recently before the new law was made more customer friendly which is now being adopted in many countries. Now in many countries the mobile number is also transferable. But still each SIM card is unique and even if you transfer your mobile number from one service provider to the other, generally you need to buy a new SIM card, give your application form for such transfer and the service provider will take care of the rest to transfer the number into the their network.
CDMA mobile handsets
Code division multiple access (CDMA) is a channel access method utilized by various radio communication technologies. It should not be confused with the mobile phone standards called cdmaOne and CDMA2000 (which are often referred to as simply "CDMA"), which use CDMA as an underlying channel access method.
In countries like India with large consumer base, the CDMA phones are also equally popular. The mobile services like TATA Indicom and Reliance Mobile started off their ventures in the Indian mobile service providers market when they just entered with the introduction of their services with CDMA handsets. However they now have their brands for the GSM services also like Tata DOCOMO and the like.
Though you can find some chip kind of thing inside the CDMA phones, it is not directly linked with the mobile number which can be readily transferred into the other CDMA phone just like in the case of GSM phones.
Why you need to know IMEI numbers for GSM and MEID number for your CDMA phone?
Though there are a lot of variations like the technical differences between these two predominant types of technologies used in the mobile handsets, the most common threat for any mobile phone owner is the theft of the mobile itself.
And if it is CDMA mobile handset which got stolen, the thief who has stolen the phone has to do some considerable effort to use it, if you had immediately blocked the mobile phone number following the theft by calling your service providers Customer care centers to block the number from illegal use.
Instead if it is your GSM mobile handset which got stolen, though you have immediately called the service provider's customer care to report about the theft to block the SIM, the thief can still use your phone by just throwing your SIM card and using his own SIM for some other use. At least he got your handset for free.
Knowing all this, have you questioned yourself at any time if there is solution to make the mobile handset useless once it is stolen. At least if all the public is aware of this point and if the mobiles which got stolen and if the mobiles become useless soon after the theft, the thieves would stop stealing mobile handsets and they might give up their thought too.
The solution is the IMEI number available for each handset with which the problem of thefts of the mobiles can be controlled if not completely avoided.
What is IMEI for GSM based mobile handsets?
IMEI is the acronym for International Mobile Equipment Identity and this 15 digit number code is unique for a particular handset. Even if you change your SIM card (SIM stands for Subscriber Identification Module) the IMEI doesn't change.
The International Mobile Equipment Identity or IMEI (pronounced /aɪˈmiː/) is a number unique to every GSM and WCDMA and iDEN mobile phone, as well as some satellite phones. It is usually found printed inside the battery compartment of the phone. It can also be displayed on the screen of the phone by entering *#06# into the keypad.
The IMEI number is used by the GSM network to identify valid devices and therefore can be used to stop a stolen phone from accessing the network. For example, if a mobile phone is stolen, the owner can call his or her network provider and instruct them to "ban" the phone using its IMEI number. This renders the phone useless, whether or not the phone's SIM is changed.
Unlike the Electronic Serial Number or MEID of CDMA and other wireless networks, the IMEI is only used to identify the device, and has no permanent or semi-permanent relation to the subscriber. Instead, the subscriber is identified by transmission of an IMSI number, which is stored on a SIM card that can (in theory) be transferred to any handset. However, many network and security features are enabled by knowing the current device being used by a subscriber.
What is MEID for CDMA mobile handsets?
A Mobile Equipment Identifier (MEID) is a globally unique number identifying a physical piece of CDMA mobile station equipment. The number format is defined by the 3GPP2 report S.R0048 but in practical terms it can be seen as an IMEI but with hexadecimal digits.
At the moment there is no standard universal keypad strokes code for finding MEID number of a given handset. The only option to know is by looking inside the phone near the battery compartment for any heading as MEID or ESN. It should be written somewhere else for safety, so that if the phone is stolen, the phone owner can immediately contact the service provider's call center to inform them about the theft and the phone can be locked by the Service provider.
However compared to GSM phones, CDMA phones are not so easy to be tampered to use a different mobile number for a particular mobile handset.
Blacklist of stolen devices
When mobile equipment is stolen or lost the owner will typically contact their local operator with a request that it should be blocked. If the local operator possesses an Equipment Identity Register (EIR), it then will put the device IMEI into it, and can optionally communicate this to the Central Equipment Identity Register (CEIR) which blacklists the device in all other operator switches that use the CEIR. With this blacklisting in place the device becomes unusable on any operator that uses the CEIR, making theft of mobile equipment a useless business proposition.
The IMEI number is not supposed to be easy to change for a common man without knowledge on electronics and programming, making the CEIR blacklisting effective. However this is not always the case: a phone's IMEI may be easy to change with special tools.
How to find the IMEI of your GSM mobile handset?
Generally all modern Nokia phones contain a sticker in or near the battery compartment showing the IMEI numbers but if even if you don't find one there is this procedure.
Just dial *#06# from the keypad of your GSM mobile handset of any make like Nokia, Samsung, LG, Sony Ericsson or any other make, and your phone displays this code immediately. Generally, this is independent of the service provider. To do this check you don't even need to have the balance in your phone. This is an in-built feature of the popular phones which are the official partners of the GSM worldwide networks.
It is always better to write down your phone make and the model number on a piece of paper when you purchase your phone and write this IMEI number you have obtained from your phone by typing *#06# as mentioned above. You can keep this piece of paper in your wallet for handy reference and you can also keep some copies at your home for extra safety.
It is strongly recommended that you write down the IMEI number along with the phone model number because, if you are using two or more mobiles, you should not get confused with them and you should not block the phone which is with you when your other phone got stolen.
Particularly in India, to avoid the fake mobile handsets which could become one of the sources of crime like terrorism, anti-national activities, etc, the Government of India has taken the serious action in this regard, to identify the mobiles with fake IMEI numbers and to disable them from use with any GSM network starting from 30th November 2009.
Hence it is worth your consideration to validate your phone's IMEI number and avoid the situation where you need to buy a new mobile handset.
How to validate your phone's IMEI number?
The procedure may vary for each country and we advise you to check with some government agency in your country which can give you credible information.
In case of India, if you are a subscriber of any of the GSM service providers like Airtel, Aircel, BSNL, Idea, Vodafone, Docomo, Loop, etc, there are these procedures:
You can validate the same by sending an SMS to 53232 or 57886 numbers in the following format:
IMEI <space> <15 digit IMEI number you found on your phone>
Example: Type IMEI 351234567891011 and SMS it to 53232.
The SMS charges are at Rs. 3/- and once you send this SMS, you should get the reply SMS something like, "Success! This IMEI belongs to: BRAND: Nokia N7-1, MANUFACTURER: Nokia Corporation, Source: MSAI, official GSM partner in India."
In case you get the reply SMS something like, "Alert!! Invalid IMEI……………………………" that means your IMEI is fake due to the unpopular brand of your mobile or if your IMEI coincides with some other phone. Generally this will not happen with the brands like Nokia, Samsung, Sony Ericsson, LG, but may happen with some cheap brands available in various countries in their local markets.
You can directly contact your service provider to get the problems resolved.
You can contact the following GII (Genuine IMEI Implant) centers. For the invalid IMEI you need to follow this procedure otherwise you will need to buy a new handset.
For the Government approved process you have to visit only the authorized GIIs. These centers can implant a new IMEI number in to your handset. For this you may need to pay Rs. 199/- as a nominal fee and you can get the receipt for the same.
While you visit any GII, along with your mobile handset, don't forget to take any one of the identity proofs like PAN card, Driving license, Voter ID card, Passport, Ration card, etc which are valid and take your passport size photographs also.
Inspired by the article in the famous Telugu newspaper EENADU http://www.eenadu.net issued in the interest of Public by MSAI.