Category Archives: Mobile Telephony

The History of Cell Phones

The history of the cell phone truly began with the creation of radio technology. Two-way radios were, after all, the ancestors of the cell phone. It wasn’t until the 1950s that what we would recognize as a cell phone was created. These were the first cell phones that allowed direct dialing. These phones, called the MTA for Mobile Telephone System A, were created by Ericsson and were released in 1956 in Sweden. They were very heavy and bulky, and the phones were usually installed in cars. Only about 150 people used the MTA system.

In 1957, Leonid Kupriyanovich created the radiophone, or a wearable mobile phone, in the USSR. These phones required a base station to operate, but each base station could be used by several customers. His phone weighted only 0.5 kg, making it much more portable that the MTA. A year later, the Altay national civil mobile phone service was developed in the USSR. This service was for car phones, and it went live in 1963.

The cell phone came to the United States in December of 1971. It started when AT&T submitted their cell network proposal to the Federal Communications Commission. The FCC kept the proposal wrapped up in committee hearings for years, but in 1982, it was finally approved.

Cell Phones in the 1970s and 1980s

The First Generation, or 1G, of true cell phones began in 1973 when Dr. Martin Cooper of Motorola called AT&T’s Joel Engel, his rival, from outdoors in New York City. He used the DynaTAC prototype, Motorola’s first cell phone. This was followed by AT&T’s Bell Labs activating their first trial cell network in Chicago in 1978 (a network not yet approved by the FCC at this time). The next year, Japan launched the first ever commercial cell network in Tokyo, and it was followed by the NMT system in Scandinavia in 1981.

While AT&T had the first network, it was Motorola that launched the first handheld cell phone. It was the Motorola Dyna 8000X, and it was approved by the FCC in 1983. This opened the floodgates, and many different cell networks and cell phones were introduced throughout the 1980s. All of these phones used an analog system, and many, especially the early phones, were designed to be installed in vehicles instead of carried around. This was because these cell phones were still quite large and heavy. Phones designed to be carried around, for example, were often the size of a standard briefcase! Towards the mid to late 80s, however, Motorola created the first truly handheld cell phones.

Cell Phones in the 1990s

The 1990s saw the creation of the second generation of cell phones. These phones began appearing on the market in 1991, and they included many of the features we now take for granted. The frequencies used for these phones were higher, and many companies dropped their first generation systems to concentrate on these new phones.

During the early 90s, companies began shifting their focus from the large car phones to handheld devices, which quickly became standard. Thanks to new advances in technologies, batteries could be made smaller and devices became more energy efficient. As demand for cell phones rose, new transmission towers had to be installed, expanding the coverage areas.

The second generation of cell phones also introduced the concept of SMS text messaging. This was initially only available on GSM networks, but it soon expanded to all digital networks. The first text was sent in the UK in 1991 by a machine, while the first person to person text was sent in 1993 in Finland. Today, texting is an integral part of cell phones.

The 1990s also saw a few other innovations come to cell phones, including the concept of downloadable content. The option to change ring tones and even download new ring tones was introduced during this time.

Cell Phones in the New Century

The Third Generation of cell phones came about with the development of the 3G networks. These networks were fairly different from the 2G networks. They were digital instead of analog, and they all confirmed to the IMT-2000 standardization, which set data transfer rates. The first of these networks was tested in Japan by NTT DoCoMo n 2001. Shortly thereafter 3G networks appeared in South Korea and the United States. By 2002, 3G networks were in almost every country.

By late 2007/early 2008, there were nearly 300 million 3G cell phone users around the world. These new cell phones have gone way beyond simply sending and making calls. Users can download games, surf the internet, take and send pictures and video, and more. Smart phones even allow users to edit documents and send emails when away from the office. While there was some doubt about the viability of the 3G network, those doubts have been put to rest.

As technology becomes more and more advances, cell phones will continue to expand. Faster networks, more features, and new ways of customizing cell phones are on the way. With phones that weigh practically nothing and fit in a pocket, it’s hard to imagine the days of the huge briefcase sized phone.

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Mosquito Ringtone: An Alarm Deaf to Adults

The mosquito ringtone, also known as Teen Buzz, is a type of ringtone that is only heard by teenagers or typically of people less than 25 years old. It is an adaptation of the technology used by the mosquito alarm, which is an electronic device that emits an extremely high frequency meant to annoy teenagers. Using this ringtone allows teenagers to receive calls and SMS messages while in school without their teachers knowing it. The mosquito ringtone is set as the same pitch as the mosquito alarm, which is at 17,800 hertz.

The Science behind the Technology

The technology takes advantage of the phenomenon called presbycusis. It is an age related hearing loss that often presents itself as an inability to hear high frequency sounds as a man or woman ages.

Men and women can hear pitches ranging as low as 20 hertz to as high as 20,000 hertz at birth. With age and exposure to loud noises, they eventually lose the ability to hear some of the high frequencies.

The Mosquito Alarm

The mosquito ringtone works the same way as the mosquito alarm. It is a commercially sold electronic alarm developed by a Welsh security company, the Compound Security Systems. The device gives off an ultrasonic sound that mimics a mosquito buzz at approximately 17.4 kHz at 85dB.

It was created by Howard Stapleton in 2005 and marketed as a safety and security tool. Its primary aim is to prevent youth nuisance and anti-social behavior, particularly gang loitering, which has been associated with vandalism, graffiti, drug abuse and distribution, and violence.

The device is primarily sold to shops and businesses to keep teenagers from loitering near their premises. The sound it emits is meant to irritate them, keeping them away. However, it does not keep its adult clients and customers away as the sound is typically unheard by adults.

The mosquito alarm is extremely popular in the United Kingdom, with some 3,500 units in use by the police and shopkeepers. It is also being sold in France, Switzerland, Australia, Canada, and the United States.


The mosquito alarm won the IG Nobel Award for peace in 2006. The IG Nobel Prizes are a spoof of the Nobel Prizes arranged by the Scientific Humor Magazine Annals of Improbable Research. The awardees of the IG Nobel Prize are best characterized as “ideas that first make people laugh, and then make them think”.

Mosquito Ringtone Effectiveness

Cell phone policies in most of the school districts in the United States allow teachers to confiscate cell phones when they are used or displayed on school grounds. Using a ringtone that an adult is deaf to allows the students to use their phones even in school.

However, most teachers question its effectiveness in circumventing these cell phone policies. Teachers purport that even though adults may not hear the phones ring, they would still see the students checking for SMS messages or answering the call. It would take incredible stealth for a student to use his or her cell phone in school grounds.

Another criticism that the mosquito ringtone had received is that not all adults are deaf to it. Moreover, its pitch at 17 kHz can be made more audible if a tone at a different frequency, such as at 22 kHz, were broadcasted constantly. The interference of the two inaudible frequencies will create acoustic beats in an audible frequency.


IMSI or International Mobile Subscriber Identity corresponds to a unique number for all mobile phone users. Basically, this is attached to your phone’s SIM (Subscriber Identity Module) and is sent to the network via your phone. The IMSI applies to all mobile networks that are interconnected with other networks. Meanwhile, it can either be provided directly along with the phone or along with your R-UIM card.

While an IMSI normally consists of 15 digits, there are others that only have 14 digits. The first three digits represents the Mobile Country Code, and then the next 2 or 3 digits represent the Mobile Network Code. The remaining digits are the mobile subscriber’s identification number within a given network.

These numbers have two functions:

  1. It identifies the GSM network operator where the user is subscribed to.
  2. It is also used to identify the unique subscriber’s identity.

The process of IMSI analysis is done to identify the network to which a given subscriber belongs to. Aside from that, it also aims to specify the access privileges that a subscriber has for a given network. This includes the roaming agreement for non-local subscribers.

Although the network to which a user subscribes allocates an IMSI, he or she can be assured of its anonymity and privacy. The number is used mainly to identify a subscriber for future exchanges.

However, if a given subscriber is not from the network of the provider, a conversion of the IMSI to a Global Title is necessary. The network can then use it to gain access to the subscriber’s data on the remote HLR. This tool is very efficient for global roaming.

Users need to negotiate a roaming agreement with their network in order for their IMSI to be recognized by other networks.

To mobile subscribers outside of North America, the IMSI is converted into a Mobile Global Title format, which still complies with the standard E.214. The E.214 standard enables the conversion of the IMSI number so it can be routed internationally.

With the rapid growth of mobile phone devices, you can also expect a continued rise in the number of mobile phone users for the next few years. Indeed, the use of IMSI will help facilitate for a smoother communication process, whether within or between other network operators.

Who Invented the Cellphone

Martin Cooper invented the cellular phone. He conceived this idea when the need for people to communicate had become more pressing. He got the concept of a mobile phone from watching Star Trek showing how the crew managed to talk to each other with their communicators.

The invention of cellphone allowed room for the technology and communications market to focus on the individual and not where the individual is. This was borne of the idea that people wanted to talk to people regardless of being in the house, in a car, or even far away from both places.

History of the Cellphone

The cellphone started as something that was slightly larger than the standard telephone. Back then, cordless phones were not even available. This kind of technology was something new as it gave people the freedom to make phone calls while moving around and being able to multitask.

The personal communications device proved to be of great use. This is especially true for the business sector. However, it took a long time for mobile phones to be available to everyone. This was because the service providers were swamped and could not perform their service properly. The demand outstripped the capacity of the providers to improve their services and technology, causing the overcrowding of the airspace.

Today, the only way for the technology to be readily available is for existing cells to be split and managed separately. The technology has to have the capacity to deal with more customers, and therefore more cells.

The Wireless Standards

The drive to improve wireless communication gave birth to two standards of communication: analog and digital.

Analog services work by radio signal communication so that standard radio frequencies could carry voice and data. Analog mobile phones work similarly to FM radios. The transmitter and the receiver tune in to equal frequency range. This works by transmitting the voice, reconstructing it with the receiver, amplifying it, and then sending it to the other side. However, this kind of service is limited because there are very limited useful channels.

The digital service works by encoding the data in binary code. The raw voice signal converts into a binary code first and then it is transmitted accordingly. The disadvantage of such technology is that the three types of wireless technologies (TDMA, CDMA, and GSM) may not be compatible with one another.

Eventually, the digital method surpassed the analog method and is the more widely used standard today.


The Global System for Mobile communication (GSM) is the most widespread mobile telephony system in the world. Over 3 billion consumers in the global market use this system. GSM’s popularity enabled the practice of international roaming, a standard process provided by many mobile phone service providers. This allows subscribers to use their cellular phones around the world.

Both signal and speech channels are digital under GSM – considered a second-generation (2G) platform. It enables data communication upgrades in the system. Among Time Division Multiple Access (TDMA), GSM, and Code Division Multiple Access (CDMA), GSM (a variation on TDMA) is most prevalent.

GSM operates by digitizing and compressing data, then sending it through a channel with a pair of user data streams, with each stream in a specific time slot. GSM’s frequency bands are 900 or 1800 MHz.

The Subscriber Identity Module (SIM) card is one of the main features of GSM. The SIM card is a detachable device containing the user’s data, such as a phone book. The SIM allows information to be stored even when switching handsets. Conversely, the user can change the SIM, thus changing service providers while keeping the handset.

GSM-based mobile phone services were launched in 1991 in Finland. GSM now represents 82.4% of all mobile connections, with over 2 billion GSM users around the globe. China, the largest GSM market, has over 370 million subscribers, with Russia following at 145 million, India at 83 million, and the United States at 78 million subscribers.

GSM is a facet of the wireless mobile telecommunications evolution that includes High-speed Circuit-Switched Data (HCSD), Enhanced Data GSM Environment (EDGE), General Packet Radio System (GPRS), and Universal Mobile Telecommunications Service (UMTS).

For more information on GSM read:

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  • ESN

    The Federal Communications Commission, or FCC, established Electronic Serial Numbers (ESNs) to identify unique mobile devices. This was mainly used for Advanced Mobile Phone System (AMPS), Time Division Multiple Access (TDMA), and Code Division Multiple Access (CDMA) phones all throughout the US. This is equivalent to the International Mobile Equipment Identity (IMEI) numbers for all Global System for Mobile communications, or GSM networks.

    The ESN serves as the wireless phone identification number and is readily embedded in its microchip. Every time a call is placed, the ESN is automatically registered at the base station so the wireless phone carrier’s main office can verify the validity of the call. It is different from the Mobile Identification number (MIN), which serves to identify the phone within a network. Both ESN and MIN are used electronically to prevent possible fraud.

    The ESN is 32 bits in length and is composed of three parts:

    1. 8-bit producer code
    2. 18-bit unique serial number
    3. The other 6 bits are set aside for use later on, but recently this has been combined with the 18-bit serial number to form a 24-bit serial number field.

    Its particular format can only recognize up to 256 individual manufacturers. However, it became apparent early on that this was going to be insufficient, so a new system was devised. The new format now consists of only the 18-bit manufacturer code and the serial number, which is also 18 bits.

    Newly assigned ESNs now follow this particular format. Meanwhile, manufacturer code 0x80 might also serve as pseudo-ESNs when reserved. It can be calculated through a EUIMID or MEID. Nevertheless, these so-called pseudo-ESNs cannot be assured of uniqueness or individuality.

    ESN Usage

    The main purpose of the ESN is to provide unique identities to mobile phones. ESNs perform the following functions:

    1. Since the ESN was designed (unlike subscription identifiers) not to be changed, this helps to uniquely identify a cellular phone. This particular use encompasses the following:
      • For identification of stolen phones;
      • For law interception;
      • For inventory purposes;
      • For warranty;
      • For provisioning.

    2. To address the radio interface of a mobile phone, especially with the lack of subscription identifier.
    3. For CAVE authentication.
    4. For registration timing.
    5. Validation for ANSI-41, also with the MIN and IMSI.
    6. For ‘back office’ systems, this is used as a unique key.

    Today, ESNs are slowly running out and are being replaced by the Mobile Equipment ID (MEID). The MEIDs are 56 bits in length.

    Cellphone Cloning

    Cell phone cloning is the practice of illegally charging phone call rates to another person’s account by duplicating the identification and serial numbers of a mobile phone. Calls from another unit are through this mobile identity number. As a result, the amount of airtime illegally consumed will be billed to the owner of the ID number to whom it is registered. This is a form of identity theft.

    Cloning is a breach to the subscriber’s privacy. The communication lines are unsecured since other people can eavesdrop on the conversations simply by using radio scanners.

    Cell phone cloning is a serious threat to the telecommunications industry and to the consumers. It has cost the wireless industry in the recent years a hefty $600 million, according to estimates.

    However, this violation can occur only to analog type of cell phones. Analog phones are most prone to cloning attacks due to their makeup and are largely misused.

    Risk of Analog Phone Use

    Analog phones carry this potential risk to real security. In fact, any person with a proper device, usually a radio receiver can listen to calls made to analog phones. In the analog system, the audio directly modulates to a carrier. The transmission flows through the same frequency wave that the FM radio uses, making it easily captured.

    How Cloning Takes Place

    Every cell phone has two unique characteristics used to distinguish itself within the cellular system. The MIN stands for Mobile Identification Number, which is quite similar to the landline system because it has three digits for area code and seven digits for the phone number. The service provider usually assigns this. It is changeable if the user wishes to transfer to another service provider.

    On the other hand, the ESN or the Electronic Serial Number comes from the manufacturer of the unit and is permanent.

    This is how cloning takes place: when making a call, the phone sends out the ESN and MIN to the subscriber network immediately. Through this pair of identification, the phone company will know where to bill the call. However, if there is right scanning equipment, it is easy to modulate another phone. It maneuvers to hold the MIN/ESN pair, allowing another person to make calls using someone else’s account.

    Unlock Mobile Phone

    Mobile phones are designed to be used with any mobile network. However, some mobile service providers electronically lock their phones as part of their marketing strategy. This obliges their subscribers to stay with that particular service provider and limits access to other features and services provided by other service providers. It also obliges a subscriber to pay for high roaming charges if the phone is taken out of their network and is used elsewhere in the world.

    Fortunately, there are techniques to resolve this problem. Techniques for unlocking mobile phones vary with each phone model and service provider. The techniques enumerated below are some of the basic procedures for unlocking a mobile phone:

    Obtain the following information:

    • Mobile phone number;
    • The network and the country to which the phone is locked;
    • Phone’s manufacturer and model number;
    • Phone’s IMEI number, which is a 15-digit serial number that can be found by typing *#06#.

    Unlocking Techniques

    • Unlocking a phone using an unlocking service phone company

    There are many companies or establishments that offer this service for a minimal fee. The unlocking will be done by the company technician and the procedure is usually quick and easy.

    • Unlocking a phone using Equipment

    Unlocking equipment are also offered by some companies. These products are often useful, albeit a bit expensive.

    • Unlocking a phone with the help of an operator

    This technique is done by calling the service provider and stating a request to unlock the phone. Some companies would ask for a few weeks notice and may even charge a fee for the service. The service provider would then give a code that should be typed into the phone to unlock it.

    • Unlocking a phone without the help of an operator

    Some service providers have a policy against unlocking their subscriber’s phones. Fortunately, most mobile phones’ unlock codes are posted in mobile forums. One could search for these and use the codes to unlock the phones.

    • Using software to unlock phones

    Another way to obtain the unlock code is by calculating the code using a data cable and special software. The unlock code obtained should specifically be for that phone model, otherwise it would not work.

    Once the phone is unlocked and serviced by a different network, the phone’s data settings must be reprogrammed in order to access the Web and send and receive picture messages. It is important to note that all phones can be unlocked.

    Additional Reading on Unlock Phone


    MTSO is an acronym for Mobile Telephone Switching Office. This is a system that connects every single cell tower to a central office or CO.

    The main purpose of the MTSO is to monitor the relative signal strength of cellular phones as indicated by each cell tower. As it processes traffic to and from the cell towers, it optimizes the amount of transferred data. Hence, it enables networks to provide more efficient wireless phone services.

    MTSO is also responsible for switching phone conversations to the cell tower that will provide the phone with the best possible reception. As a wireless call moves away from the current cell tower maintaining it, a computer in the MTSO would keep track of the call. Once the computer has determined the appropriate time, it will transfer the call to another cell tower that will give better reception. This transition happens so fast that the persons involved in the call do not notice it.

    The MTSO controls other operations related to wireless phone calls, such as call verification and billing. It can accurately determine the source of received calls as well. This system also ensures that the fees being charged to network subscribers are accurate at all times.

    Due to the unique features of the MTSO, most commercial phone companies have incorporated it to their system. When this system is used, the amount of errors encountered is minimized. This is another reason the switching office gained recognition from groups within the field of telecommunications.


    The International Mobile Equipment Identity (IMEI) is a unique 15- or 17-digit code used to determine a mobile station or satelite phone to a UMTS or GSM network. It is usually located underneath the phone’s battery. The IMEI is a useful means of preventing a stolen phone from being used to access a network.

    The owner of a stolen phone can ask his mobile network provider to shut off the phone using the IMEI. The service provider can then quickly and easily ban the phone from the network. This will make the phone useless, even if the SIM is replaced. An IMEI is saved on the phone and not on the SIM card.

    An IMEI is only used to identify the device. It has no direct link to a specific individual or organization. It is different from a Electronic Serial Number (ESN) and a Mobile Equipment Identifier (MEI) that can link an individual to the device.

    How to Find an IMEI

    There are several ways to find a phone’s IMEI:

    1. Remove the battery of your phone. You can simply find it on the white label under the battery. You will have to copy the first 15 numbers for future reference. The IMEI has no slashes or letters.
    2. If the IMEI is not found on the back of your phone, return the battery to its slot and turn the phone on. Let the phone initialize before continuing. On the keypad of the phone, enter *#06#. Upon pressing the last #, the phone will display the IMEI number composed of 15 numbers. Copy it for future purposes.
    3. If you have a SIM card, check the Menu of the phone. Scroll through it and look for the IMEI or SIM ID menu. Enter it to find the IMEI number.
    4. For older phones with a SIM card, press the right arrow and look for the IMEI menu. Then press Enter for the IMEI to be displayed. If you just see seven digits, press the Menu key and the Next key to show the rest of the code.
    5. If your phone is a Motorola, enter #,*, (menu). Then press the right arrow immediately. Press these keys without pausing. The IMEI will then be displayed.

    Further Reading on IMEI’s


    HSDPA stands for High-Speed Downlink Packet Access. It is also referred to as 3.5G technology in mobile protocol. Installation of the HSDPA feature in cell phones can provide higher speed of data transmission during a downlink process.

    It is promoted primarily for mobile phone access to the Internet in the same way as DSL is for residential access. Users get more pieces of data in a shorter time. With that, providers can catch more users to create more revenue.

    This innovation in telephony is an upgrade of the WCDMA, an improvement in cellphone broadband data service. It is capable of increasing the capacity of a system. It allows service providers to offer more competent services through the same wireless delivery service frequency used by WDCMA. The projected effects have been viewed as a win-win solution for both the end-users and the providers of data service.

    What Users can Expect

    With the speed of data transfer reaching up to a peak rate of 14,400 kbps, HSDPA brings a better experience for its end-users. Data will have a shorter time to travel; the higher the Transmission Time Interval (TTI), the faster the downloading time is. As data comes more rapidly, the cost of access will be reduced too. If HSDPA will be made available to a wider market of mobile phone users, stalling on downloads will be a thing of the past.

    Benefits to the Operator

    Production costs will be greatly reduced because of the intensified system capacity. Through the process called shared channel transmission, there will be no need for operators to install a new set of carriers. It will use the existing spectrum of data and voice carriers currently used by the technology versions in operation.

    HSDPA handles faster retransmission to facilitate an increase in capacity. Another remarkable aspect of the HSDPA feature is its fast scheduling rate, giving priority to users who have the most advantageous channel conditions.

    As data will come faster, many end-users will be serviced at a higher speed. Hence, the service can be extended to a wider market.

    HSDPA will continue to evolve over time as special upgrades are always introduced. However, it still requires more refinement to make it an alternative to the current 3G technology, which has delivered short of its promised efficiency.

    Related Articles on HSDPA

    Cell Phone Signal Boosters

    If you are one of the 35% of people in the world who own cellular phones and have problems with signal, you are advised to use a cell phone signal booster.

    How it Works

    The cell phone signal booster, also known as an internal “extra” antenna, reduces static to enhance your cell phone’s signal. Static often occurs in thick-walled buildings, hallways, far flung areas, and tunnels. This internal antenna seizes some stray radiation generated by your cell phone and radiates the signal back. It improves the overall operation of your cell phone.

    Another famous form of cell phone signal booster is the one mounted in cars, boats, trucks, or even recreational vehicles. This operates with the same principle of the internal antenna; however, it is separated from the phone itself. It is wireless and promises outstanding indoor signal everywhere. It performs slightly better than the internal cell phone signal boosters because it is more exposed to the signal.

    The Benefits of Using a Cell Phone Signal Booster

    Cell phone signal boosters are known to lessen dropped calls, broaden the range of your cell phone, and enhance your signal up to 800%. This internal antenna is widely known to be ultra thin and can easily be placed in your cellular phone’s battery compartment, beneath your internal battery.

    Signal improvement, through a cell phone signal booster, enhances services other than calling such as Instant Messaging, Internet, 3G data, and picture mailing. This product is also known to improve your battery life because it reduces the power needed for transmission.

    Other Tips

    If you want to get the most out of your cell phone signal booster, strip off its protective layer. By then, the adhesive part of the booster is exposed. Then you can place the booster beneath the internal battery.

    Universal cell phone signal boosters are now available almost everywhere, especially in the Internet. They work basically anywhere and anytime. Most universal cell phone signal boosters work on digital, tri-band, analog, dual-band, and quad-band cell phones. In fact, the latest ones can work with PDAs! They also work well with just about any service provider.

    With this amount of convenience, a cell phone signal booster is truly a good investment for those who depend on their cell phones all the time.

    Additional Reading on cell phone signal booster