THE MOBILE PHONEPART 1 The mobile phone working was not much known till 1995for many of us inTelecom Department itself. It was somewhere in the end of the year, the firstintroductory training about the functioning was given to us by a lecturer inChennai training center who had worked in a mobile project at Dubai.
Now the mobile phones are widely used and they havereplaced to a great extent the Land phones. When mobile was misplaced it was searched by dialingfrom the land phone. But when mobilephone towers were struck down for days/weeks it was land phone which helped thecustomers. Customersfound the clarity in the land phone is much more. There is no problem of rangeand many started keeping one land phone and one or two mobiles. The policeusing walki- talki are the first type of mobile application known to us. Theinitial mobile phones were very large with an antenna to a length of at least3-4 inches. A phoneworking without dial tone was something new to us. An interestinglook in to mobile phone and it’s working with nostalgic memories. Some information are compiled from Google search also for better clarity Gopalakrishnan 22-12-2022 1 When didmobile communication started in India? In 1995, a few months after mobile telephony was opened up toprivate participation, Essarbecame the first company to start GSM operations in Delhi under the brand name,Essar Cellphones. The earlier operators were Hutch, idea,Aircel, airtel, BPL etc.BPL stopped its operation. I was having a BPL SIM phone which enabled meto talk to my son in Soudi Arabia for one or two minutes. The cost of mobile phone and mobile charges werevery high. A mobile PCO 3 minutes local call was charged Rs 8-00. Incomingcalls were charged. Phones were charged using charging card from dealers. Aircel joinedwith Airtel. Hutchbecame Vodafone and about a year back idea too joined and became VI. Now threeoperators are more known- BSNL, Airtel, VI. 2. Preferenceto BSNL. BSNL started mobile communication in 2002. In Chennai mobilecommunication was started a little later than in Kerala. I was part of planningmobile network of Kerala. Tower locations, substations, mobile exchange etc. Comparing to other operators BSNL had more towers andsubstations and wider coverage. Hence those who travel more prefer BSNL SIM nowalso. There was high demand for BSNL mobile and especially prepaid. Initially all companies just got filled up a form withphoto and address and supplied SIM. If my information is correct all companies hadprepaid initially and later introduced postpaid. 3. Why prepaidis preferred. >From prepaid mobiles one could make internationalcalls. Postpaid is limited to >India and a huge deposit was required to permitinternational calls. When I came to Chennai, as formerAssistant General Manager BSNL, because of the high demand I could not get aBSNL SIM. I purchased Airtel prepaid SIM and converted to postpaid with a gooddeposit of money. Very late I could purchase a BSNL prepaid SIM. 4. Linking toAadhar. After Aadhar became an identity of persons, mobilesare linked to aadhar. Now no prepaid or postpaid mobile can function withoutlinking to aadhar/passport etc.This gives an accountof mobiles working with different companies. 5. New SIM If a mobile phone is lost immediately the number is blockedon request and a new SIM is given with the same number. I understand there is maximum number of SIMs aperson can hold. Present daymobile can do a lot of functions. Even one can have a mobile phone for such purposes. One example is storing important mobile numbershandy, use for alarm, use as calculator, camera etc. I use one of my oldmobiles for these purposes. Only with SIM one can make/receive a call. Now all mobiles are with dual SIM. Many use one forreceiving calls and another for making calls. The advantage is one SIM can becharged with validity and another for validity and speaking. 6. How mobilesare working Without going to more complicatedtechnical details I write below howthe mobile phone is working. In mobile communications, high-frequencyelectromagnetic fields are used for wireless transmission of voice and data. Infree space they propagate as waves at the speed of light while being able totransmit energy and information over long distances. A mobile phone is an electronic device used for mobiletelecommunications over a cellular network of specialized base stations known as cellsites. A cell phone offers full Duplex Communication and transferthe link when the user moves from one cell to another. As the phone user movesfrom one cell area to another, the system automatically commands the mobilephone and a cell site with a stronger signal, to switch on to a new frequencyin order to keep the link. Mobile phone isprimarily designed for Voice communication. In addition to the standard voice function, newgeneration mobile phones support many additional services, and accessories,such as SMS for text messaging, email, packet switching for access to theInternet, gaming, Bluetooth, camera with video recorder and MMS for sending andreceiving photos and video, MP3 player, radio and GPS. 6a Cellularsystem The cellular system is the division of an area intosmall cells. This allows extensive frequency reuse across thatarea, so that many people can use cell phones simultaneously. Cellular networkshas a number of advantages like increased capacity, reduced power usage, largercoverage area, reduced interference from other signals etc. 6b FDMA andCDMA Systems Frequency Division Multiple Access (FDMA) and CodeDivision Multiple Access (CDMA) were developed to distinguish signals fromseveral different transmitters. In FDMA, the transmitting and receivingfrequencies used in each cell are different from the frequencies used in theneighboring cells. The principle of CDMA is more complexand the distributed transceivers can select one cell and listen to it. Other methods includePolarization Division Multiple Access (PDMA) and Time Division Multiple Access(TDMA). Time division multiple access is used in combination with either FDMAor CDMA to give multiple channels within the coverage area of a single cell. 7. Codes in theMobile Phone Mobile phones have special codes associated with them.These include: ElectronicSerial Number (ESN) -Unique 32-bit number programmed in the phone MobileIdentification Number (MIN) – 10 digit number derived from the phone’s number. SystemIdentification Code (SID) – unique 5 digit number that is assigned to each carrier by the FCC. ESN is a permanent part of the phone while MIN and SIDcodes are programmed in the phone when a service plan is selected andactivated. 8. Mobile phone Mobile phone is a Duplex device. When we use one frequency for talking, a second separate frequency isused for listening. So that both the people on the call can talk at once. TheMobile phone can communicate on 1,664 channels or more. The Mobile phonesoperate within the cells, so that it is easy to switch on to different cells asthey move around. A person using a cell phone can drive hundreds of kilometersand can maintain a conversation during the entire time because of the cellularapproach. 9 Activation ofSIM Card SIM card (Subscriber Identification Module (SIM)) is atype of Smart card used in mobile phone. The SIM is a detachable smart cardcontaining the user’s subscription information and phone book. This allows theuser to retain his or her information even after switching off the handset.Alternatively, the user can also change service providers while retaining thehandset simply by changing the SIM. SIM card securely stores the servicesubscriber key having 15 digits. My note- Now retaining the same MIN now customers canchange the service provider. The digits of the key are: First 3 digits – Mobile country code. For India 091 Second 2 digits – Mobile network code Third 10 digits – Mobile station identification number My note- Network code is integrated with mobilenumber. For BSNL 94, Airtel 98 etc. I will continuein next posting -- You received this message because you are subscribed to the Google Groups "Thatha_Patty" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/thatha_patty/1360062685.2321044.1671713827486%40mail.yahoo.com.
