Tuesday, March 27, 2007

GSM frequency bands, 3G and IMEI

GSM frequency bands used around the world are:
850 MHz (In America)
900 MHz (In Europe)
1800 MHz (In Europe and Asia)
1900 MHz (In America)


In mobile phones, dual band refers to functionality that allows a mobile phone to support two frequency bands out of the four major GSM bands. A cellphone with dual band 850/1800 MHz, for example, will work in both the United States (850 MHz) and India (1800 MHz).

Various countries use different frequency bands for their mobile networks, and a triband phone can be used on three of these bands.Generally these tri band mobile are manufactured to support two home countrys networks and one for roaming.

Triband phones are mobile phones that support the GSM 900/1800/1900 MHz bands (commonly sold in Europe, Asia, and Africa), or alternatively the 850/1800/1900 bands (commonly sold in the Americas).

Literally speaking quad band mobile phones means the phones which support all the GSM frequency bands. These are only known as world phones.

When gifting mobile phones..
Make sure that the mobile you are presenting is world phone.
When bringing mobiles to India(from abroad) make sure that their IMEI No starts with 3, so that its compatible with the networks Indian networks.


3G is short for third-generation technology. The services associated with 3G provide the ability to transfer simultaneously both voice data (a telephone call) and non-voice data (such as downloading information, exchanging email, and instant messaging). In marketing 3G services, video telephony has often been used as the killer application for 3G.
The first country which introduced 3G on a large commercial scale was Japan. In 2005, about 40% of subscribers used 3G networks only, with 2G being on the way out. It was expected that the transition from 2G to 3G would be largely completed during 2006, and upgrades to the next 3.5G stage with 3 Mbit/s data rates were under way.

Usage of 3G networks in India is yet to be approved by government.

International Mobile Equipment Identity

The International Mobile Equipment Identity is a number unique to every GSM. It is printed on the phone underneath the battery and can also be found by dialing the sequence *#06# into the phone. The IMEI (14 digits plus check digit) or IMEISV (16 digits) includes information on the origin, model, and serial number of the device.

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, regardless of whether the phone's SIM is changed.

Record the serial number (IMEI) of the handset in a safe place (enter *#06# on most GSM handsets to receive a 15 digit serial number).

IMEI information from a GSM
On many devices the IMEI number can be retrieved by entering *#06#.
Retrieving from nokia mobile phones by pressing *#92702689# (*#WAR0ANTY#), this opens the warranty menu in which the first item is the serial number (the IMEI).

IMEI numbers of cellular phones connected to a GSM network are stored in a database (EIR - Equipment Identity Register) containing all valid mobile phone equipment.
When a phone is reported stolen or is not type approved, the number is marked invalid.

Central Equipment Identity Register (CEIR)
If a mobile handset is lost or stolen, as the owner or operator of the device, you can contact the CEIR which will blacklist the device in all currently operating switches. This makes the lost or stolen handset unusable. The action of blacklisting stolen mobile handsets is seen as a deterrent to crime, however, it is possible to change an IMEI with special tools and there are certain mobile networks that do not automatically blacklist handsets registered with the CEIR. Current statistics state that about 10 % of current IMEI's in use today are not unique or have been reprogrammed (hacked).

International Mobile Equipment Identity Software Version (IMEISV)
For example the IMEI code 35-209900-176148-1 or IMEISV code 35-209900-176148-23 tells us the following:
TAC(Type Allocation Code): 352099 so it was issued by the BABT and has the allocation number 2099
FAC(Final Assembly Code): 00 so it was numbered during the transition phase from the old format to the new format (described below)
SNR: 176148 - uniquely identifying a unit of this model
CD: 1 so it is a GSM Phase 2 or higher
SVN: 23 - The 'software version number' identifying the revision of the software installed on the phone. 99 is reserved

"New IMEIs can be programmed into stolen handsets and 10% of IMEIs are not unique." According to a BT-Cellnet spokesman quoted by the BBC.

In many countries changing the IMEI or IMEISV is considered as a crime.

Comments and suggestions are welcome about the content!!

Manoranjan Reddy Mandadi


Anonymous said...

thanks for the information.

Unknown said...

Thanks for letting us know about the GSM cell phone technology. In fact almost all parts of the world operate on GSM technology, except USA and Canada. Originally GSM operated at a frequency of 900 MHz, which is being continuously upgraded and now works on 1,800 MHz service. With a GSM phone, you can access service in 212 different countries. Some of the mobile phones available in the United States and Canada operate on GSM, but most of them are of a different frequency band. The GSM service available in North America is of a totally different frequency of 1,900 MHz and sometimes 850 MHz, which is different from the standard of 1,800 MHz. Not all countries in the world use the standard 900/1,800 MHz GSM. The exceptions being, Canada, Mexico, Japan, Korea, and some Central/South American countries, with some limited coverage of the standard GSM networks. For more information visit sell mobile phones .