How Mobile Telephone Calls Are Handled

Telephone customer (1) dials 'Long Distance' and asks to be connected with the mobile services operator, to whom he gives the telephone number of the vehicle he wants to call. The operator sends out a signal from the radio control terminal (2) which causes a lamp to light and a bell to ring in the mobile unit (3). Occupant answers his telephone, his voice traveling by radio to the nearest receiver (4) and thence by telephone wire.

To place a call from a vehicle, the occupant merely lifts his telephone and presses a 'talk' button. This sends out a radio signal which is picked up by the nearest receiver and transmitted to the operator.[BLR1]

(The above accompanies a Bell Laboratories Record illustration, from the 1946 article first describing the system. It's a 346k download.)

The 20 watt mobile sets did not transmit back to the central tower but to one of five receivers placed across the city.[BLR2] Once a mobile went off hook all five receivers opened. The Mobile Telephone Service or MTS system combined signals from one or more receivers into a unified signal, amplifying it and sending it on to the toll switchboard. This allowed roaming from one city neighborhood to another. Can't visualize how this worked? Imagine someone walking through a house with several telephones off hook. A party on the other end of the line would hear the person moving from one room to another, as each telephone gathered a part of the sound.

One party talked at a time with MTS. You pushed a handset button to talk, then released the button to listen. (This eliminated echo problems which took years to solve before natural, full duplex communications were possible.) Mobile telephone service was not simplex operation as many writers describe, but half duplex operation. Simplex uses only one frequency to both transmit and receive. In MTS the base station frequency and mobile frequency were offset by five kHz. Privacy is one reason to do this; eavesdroppers could hear only one side of a conversation. Like a citizen's band radio, a caller searched manually for an unused frequency before placing a call. But since there were so few channels this wasn't much of a problem. This does point out radio-telephones' greatest problem of the time: too few channels.

This system presaged many cellular developments, indeed, Bell Laboratories' D.H. Ring articulated the cellular concept one year later in an unpublished paper. Young states all the elements were known then: a network of small geographical areas called cells, a low powered transmitter in each, the cell traffic controlled by a central switch, frequencies reused by different cells and so on. Young states that from 1947 Bell teams "had faith that the means for administering and connecting to many small cells would evolve by the time they were needed." [Young] While recognizing the Laboratories' prescience, more mobile telephones were always needed. In every city where mobile telephone service was introduced waiting lists developed, growing every year. By 1976 only 545 customers in New York City had Bell System mobiles, with 3,700 customers on the waiting list. Around the country 44,000 Bell subscribers had AT&T mobiles but 20,000 people sat on five to ten year waiting lists. [Gibson] Despite this incredible demand it took cellular 37 years to go commercial from the mobile phone's introduction. But the FCC's regulatory foot dragging slowed cellular as well. Until the 1980s they never made enough channels available; as late as 1978 the Bell System, the Independents, and the non-wireline carriers divided just 54 channels nationwide. [O'Brien] That compares to the 666 channels the first AMPS systems needed to work.

In mobile telephony a channel is a pair of frequencies. One frequency to transmit on and one to receive. It makes up a circuit or a complete communication path. Sounds simple enough to accommodate. Yet the radio spectrum is extremely crowded. In the late 1940s little space existed at the lower frequencies most equipment used. Inefficient radios contributed to the crowding, using 60 kHz to send an signal that can now be done with 10kHz or less. But what could you do with just six channels, no matter what the technology? Users by the scores vied for an open frequency. You had, in effect, a wireless party line, with perhaps forty subscribers fighting to place calls on each channel. Most mobile telephone systems couldn't accommodate more than 250 people. There were other problems.

Radio waves at lower frequencies travel great distances, sometimes hundreds of miles when they skip across the atmosphere. High powered transmitters gave mobiles a wide operating range but added to the dilemma. Telephone companies couldn't reuse their precious channels in nearby cities, lest they interfere with their own systems. They needed at least seventy five miles between systems before they could use them again. While better frequency reuse techniques might have helped, something doubtful with the technology of the times, the FCC held the key to opening more channels for wireless.

In 1947 AT&T began operating a "highway service", a radio-telephone offering that provided service between New York and Boston. It operated in the 35 to 44MHz band and caused interference from to time with other distant services. Even AT&T thought the system unsuccessful.

In that same year the Bell System asked the FCC for more frequencies. The FCC allocated a few more channels in 1949, but gave half to other companies wanting to sell mobile telephone service.

Berresford says "these radio common carriers or RCCs, were the first FCC-created competition for the Bell System" He elaborates on the radio common carriers, a group of market driven businessmen who pushed mobile telephony in the early years further and faster than the Bell System:

The telephone companies and the RCCs evolved differently in the early mobile telephone business. The telephone companies were primarily interested in providing ordinary, 'basic' telephone service to the masses and, therefore, gave scant attention to mobile services throughout the 1950s and 1960s. The RCCs were generally small entrepreneurs that were involved in several related businesses-- telephone answering services, private radio systems for taxicab and delivery companies, maritime and air-to-ground services, and 'beeper' paging services. As a class, the RCCs were more sales-oriented than the telephone companies and won many more customers; a few became rich in the paging business. The RCCs were also highly independent of each other; aside from sales, their specialty was litigation, often tying telephone companies (and each other) up in regulatory proceedings for years.

As proof of their competitiveness, the RCCs serviced 80,000 mobile units by 1978, twice as many as Bell. This growth built on a strong start, the introduction of automatic dialing in 1948. On March 1, 1948 the first fully automatic radiotelephone service began operating in Richmond, Indiana, eliminating the operator to place most calls. [McDonald] The Richmond Radiotelephone Company bested the Bell System by 16 years. AT&T didn't provide automated dialing for most mobiles until 1964, lagging behind automatic switching for wireless as they had done with landline telephony. (As an aside, the Bell System did not retire their last cord switchboard until 1978.) Most systems, though, RCCs included, still operated manually until the 1960s. Interestingly, some claim the Swedish Telecommunications Administration's S. Lauhrén designed the world's first automatic mobile telephone system, with a Stockholm trial starting in 1951.

I've found no literature to support a claim they were the first, before the 1948 Richmond Telephone Company service. For completeness, I should mention the following.

Anders Lindeberg of the Swedish Museum of Science and Technology does point out the link I provide in the preceding paragraph is "a summary from an article in the yearbook "Daedalus" (1991) for the Swedish Museum of Science and Technology http://www.tekmu.se/

The Swedish original article is much more extensive than the summary." He adds that "The Mobile Phone Book" by John Meurling and Richard Jeans, ISBN 0-9524031-02 published by Communications Week International, London in 1994 does briefly describe the "MTL" from 1951.

Speaking of Sweden, let's go to Europe to read about a typical radio-telephone unit, something similar to American installations:

It was in the mid-1950's that the first phone-equipped cars took to the road. This was in Stockholm - home of Ericsson's corporate headquarters - and the first users were a doctor-on-call and a bank-on-wheels. The apparatus consisted of receiver, transmitter and logic unit mounted in the boot of the car, with the dial and handset fixed to a board hanging over the back of the front seat. It was like driving around with a complete telephone station in the car. With all the functions of an ordinary telephone, the telephone was powered by the car battery. Rumor has it that the equipment devoured so much power that you were only able to make two calls - the second one to ask the garage to send a breakdown truck to tow away you, your car and your flat battery. . . These first car phones were just too heavy and cumbersome - and too expensive to use - for more than a handful of subscribers. It was not until the mid-1960's that new equipment using transistors were brought onto the market. Weighing a lot less and drawing not nearly so much power, mobile phones now left plenty of room in the boot - but you still needed a car to be able to move them around.

In 1956 the Bell System began providing manual radio-telephone service at 450 MHz, a new frequency band assigned to overcrowding. AT&T did not automate this service until 1969. In 1958 the innovative Richmond Radiotelephone Company improved their automatic dialing system. They added new features to it, including direct mobile to mobile communications.

Other independent telephone companies and the Radio Common Carriers made similar advances to mobile-telephony throughout the 1950s and 1960s. If this subject interests you, The Independent Radio Engineer Transactions on Vehicle Communications, later renamed the IEEE Transactions on Vehicle Communications, is the publication to read during those years.

In that same year the Bell System petitioned the FCC to grant 75 MHz worth of spectrum to radio-telephones in the 800 MHz band. The FCC had not yet allowed any channels below 500MHz, where there was not enough continuous spectrum to develop an efficient radio system. Despite the Bell System's forward thinking, the FCC sat on this proposal for ten years and only considered it in 1968 when requests for more frequencies became so backlogged that they could not ignore them.

In 1964 the Bell System introduced Improved Mobile Telephone Service or IMTS, a replacement to the badly aging Mobile Telephone System. It worked in full-duplex so people didn't have to press a button to talk. Talk went back and forth just like a regular telephone. It finally permitted direct dialing, automatic channel selection and reduced bandwidth to 25-30 kHz.

Before leaving conventional radio telephony I should mention fraud. As telephone folks were well acquainted with landline toll fraud, begun in earnest in the late 1960s, so they were aware of wireless fraud. Here's a summary from a 1985 article in Personal Communications Technology Magazine: "The earliest form of mobile telephony, unsquelched manual Mobile Telephone Service (MTS), was vulnerable to interception and eavesdropping. To place a call, the user listened for a free channel. When he found one, he would key his microphone to for service: 'Operator, this is Mobile 1234; may I please have 555-7890.' The operator knew to submit a billing ticket for account number 1234 to pay for the call. So did anybody else listening to the channel--hence the potential for spoofing and fraud.

Squelched channel MTS hid the problem only slightly because users ordinarily didn't overhear channels being used by other parties. Fraud was still easy for those who turned off the squelch long enough to overhear account numbers.

Direct-dial mobile telephone services such as Improved Mobile Telephone Service (IMTS) obscured the problem a bit more because subscriber identification was made automatically rather than by spoken exchange between caller and operator. Each time a user originated a call, the mobile telephone transmitted its identification number to the serving base station using some form of Audio Frequency Shift Keying (AFSK), which was not so easy for eavesdroppers to understand.

Committing fraud under IMTS required modification of the mobile--restrapping of jumpers in the radio unit, or operating magic keyboard combinations in later units--to reprogram the unit to transmit an unauthorized identification number. Some mobile control heads even had convenient thumb wheel switches installed on them to facilitate easy and frequent ANI (Automatic Number Identification) changes."

History of mobile phones

This history of mobile phones chronicles the development of radio telephone technology from two-way radios in vehicles to handheld cellular communicating devices.
In the beginning, two-way radios (known as) were used in vehicles such as taxicabs, police cruisers, ambulances, and the like, but were not mobile phones because they were not normally connected to the telephone network. Users could not dial phone numbers from their mobile radios in their vehicles. A large community of mobile radio users, known as the, popularized the technology that would eventually give way to the mobile phone. Originally, mobile phones were permanently installed in vehicles, but later versions such as the so-called transportables or "bag phones" were equipped with a so that they could also be carried, and thus could be used as either mobile or as two-way radios. During the early 1940s, Motorola developed a backpacked two-way radio, the and later developed a large hand-held two-way radio for the US military. This battery powered "Handie-Talkie" (HT) was about the size of a man's forearm.
In Europe, radio telephony was first used on the first-class passenger trains between Berlin and Hamburg in 1926. At the same time, radio telephony was introduced on passenger airplanes for air traffic security. Later radio telephony was introduced on a large scale in German tanks during the. After the war German police in the British zone of occupation first used disused tank telephony equipment to run the first radio patrol cars. In all of these cases the service was confined to specialists that were trained to use the equipment. In the early 1950s ships on the Rhine were among the first to use radio telephony with an untrained end customer as a user.

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HTC - Lancaster

HTC - Lancaster
Network GSM850 GSM1800 GSM1900 UMTS dual-band American 3G (850/1900 MHz)
Size 109 x 54 x 17.10 mm
Case Type Slider
Weight 110gm
Internal Antenna
Display
Resolution - Pixels
Colors
Size 2.8"
Accumulator
Capacity 1350 mAh
Type
Talk Time
Stand by time
Ring Tones / Sound Functions
Polyphonic
MP3 Support MP3, AAC, AAC+, WMA, WAV , Music Player
FM Radio
Voice Recorder

Voice Command
Hands-free mode
Push-to-talk
3D-Sound
Camera
Resolution 3 MP
Zoom
Flash
Video

Internet
GPRS
WAP
EDGE
HSCSD
HTML Browser

Message Services
EMS
MMS
T9

Other Parameters
RAM
Phonebook Records
Memory Slot

Bluetooth

IR
USB

Change Panel

Blackberry Promises Four New Devices for Its Admirers

Blackberry has officially announced four new devices, which will be released via AT&T this year. Magnum, and Gemini are the three devices that have been in news for few days. Pearl 3G is the newest device in the list. Here are the few important specifications of these devices.
Blackberry Onyx is certainly the most interesting cell phone on the list, as it has already aroused curiosity among the people. The cell phone will be admired for its beautiful display and support for Wi-Fi, GPS and 3G HSDPA. Along with that, a 3.2MP camera is also accommodated in the list. The hottest aspect of the device is that it has been designed as a compact shell with spectacular looks.
Blackberry Magnum is going to support full QWERTY keyboard as well as touch screen functionality. Also, it will provide support to 3G, GPS, Wi-Fi and HVGA display as well. The is expected to adopt the portfolio similar to Blackberry Bold.
Blackberry Gemini is going to accommodate a powerful CPU, along with a QVGA display. The user will also be facilitated with micro SD card slot as well as a 3.5mm audio jack. A 2MP camera is also going to mark its presence in the device and it might also support GPS.
HSDPA, GPS and micro SD card support are some of the features disclosed for 3G Pearl. However, other specifications about the device will be disclosed soon.
The release dates of all the devices have not been disclosed, but one can expect Blackberry Onyx to appear soon on the shelves.

HTC Touch P3450 Cell Phone

The HTC Touch is the first device to feature TouchFLO, the new underlying touch screen technology developed by HTC. Consumers simply sweep their finger up the display to launch an animated, three-dimensional interface comprising three screens: Contacts, Media and Applications. The interface can be spun by swiping a finger right or left across the display, providing...

The HTC Touch is the first device to feature TouchFLO, the new underlying touch screen technology developed by HTC. Consumers simply sweep their finger up the display to launch an animated, three-dimensional interface comprising three screens: Contacts, Media and Applications. The interface can be spun by swiping a finger right or left across the display, providing efficient access to the features consumers use most. TouchFLO also enhances finger touch scrolling and browsing of Web pages, documents, messages and contact lists.


Leveraging the broad functionality of Windows Mobile 6 Professional, the HTC Touch includes Outlook Mobile, Office Mobile, Windows Live and the capabilities to run thousands of third-party applications. Users can surf the web with Internet Explorer, send and receive emails, chat on Messenger and send files to their own web space through Windows Live.


Other HTC Touch details include:

Dimensions: 99.9mm (L) x 58mm (W) x 13.9mm (T)

Weight: 112g with battery

1GB microSD storage card included / 64MB RAM, 128MB ROM

2.8" LCD touch screen with backlight, 240 x 320 dots resolution with 65,536 colours

Battery Life: Rechargeable Li-Ion battery with a capacity of 1100 mAh

Standby time: Up to 200 / Talk time: Up to 5 hours

Camera: 2.0 mega-pixel CMOS colour camera

Windows Mobile 6 Professional with Direct Push Email and HTML email support

Wireless Connectivity: GSM/GPRS/EDGE Tri-band: 900, 1800,1900, Wi-Fi: IEEE 802.11 b/g and Bluetooth 2.0

Choice of two colors at launch - elegant soft black or alluring wasabi green

Nokia N96 Cell Phone

Nokia N96 Cell Phone


This product is designed for great video and live TV. Turn on and enjoy prime time mobile entertainment that suits your schedule.
You can enjoy high-quality video on a large bright display with superb sound, store more of your videos, musics, pictures and maps with massive storage, and choose from several high-speed connectivity options to access content and services.

Nokia N95

It's GPS. It's a photo studio. It's a mobile disco. It's the world wide web. It's anything you want it to be. Explore the internet with 3.5G ease. Navigate the world with interactive maps and purchasable local city guides. Download your favorite music tracks. And capture it all with 5 megapixel clarity and Carl Zeiss optics. Experience the true power of multimedia

Apple iPhone 3G 16GB

Apple iPhone 3G 16GB (Black)iPhone combines three products - a revolutionary mobile phone, a widescreen iPod with touch controls, and a breakthrough Internet communications device with desktop-class email, web browsing, maps, and searching - into one small and lightweight handheld device. iPhone also introduces an entirely new user interface based on a large multi-touch display and pioneering new




Carrier: AT&T
Color Reference: Black
Storage Capacity: 16 GB
Cell Phone Type: Bluetooth, Camera, Digital Player, GPS, MP3
Product Line: iPhone
Cell Network Technology: WCDMA, GSM
Wireless Technology: Wi-Fi, Bluetooth
Weight: 4.7 oz.

Nokia N76

Nokia N76Intelligent inside, dynamic outside. The Nokia N76 is a revolution in one-touch technology. Shoot high-resolution images, play thousands of songs, and connect instantly to the web - without ever opening your device. Search and surf with advanced web navigation. The Nokia N76 is the multimedia computer that lets you do it all - and with personal color options, tempered...
Intelligent inside, dynamic outside. The Nokia N76 is a revolution in one-touch technology. Shoot high-resolution images, play thousands of songs, and connect instantly to the web - without ever opening your device. Search and surf with advanced web navigation. The Nokia N76 is the multimedia computer that lets you do it all - and with personal color options, tempered glass, and mirrored steel, you'll stand out doing it.












Storage Capacity: 26 MB
Cell Phone Type: Push to Talk, Bluetooth, MP3, Video, Camera, Digital Player, FM Radio
Cell Network Technology: WCDMA, GSM
Wireless Technology: Bluetooth
Weight: 4.1 oz.

BlackBerry Curve 8310

BlackBerry Curve 8310Featuring a metallic finish, clean lines and soft edges, the BlackBerry Curve 8310 smartphone is the smallest and lightest BlackBerry smartphone ever to come with a full QWERTY keyboard.
It's packed with incredible features, including a camera, a multi-media player, built-in GPS, expandable memory, Voice Dialing, BlackBerry Maps and trackball navigation. Plus, you get




Carrier: AT&T
Color Reference: Titanium
Cell Phone Type: GPS, MP3
Product Line: BlackBerry
Manufacturer Product Manual: Manufacturer Product Manual
Cell Network Technology: GSM
Wireless Technology: Bluetooth

Sony Glasstron

There's no denying that a big screen provides the ultimate in viewing. Problem is, a big screen keeps you pretty much anchored to your living room or den. Fortunately, Sony has developed an extraordinary solution.

Introducing the Glasstron Audio/Video/PC Headset, Sony's newest portable big screen experience. This personal video theater projects a 52" virtual image of your program inside lightweight, comfortable and futuristic-looking glasses.

Simply slip on Glasstron, connect to a video source or a PC, and you're ready for an eye-opening view of your favorite programming, complete with high-fidelity stereo sound.

Sony's Glasstron Audio/Video/PC Headset is so lightweight and compact you can take it just about anywhere. Whether you're relaxing on the couch, enjoying the great outdoors, or flying cross-country, Glasstron is designed to go to great lengths to enhance your viewing pleasure.

Note: The Sony Glasstron is no longer being manufactured or supported. Limited stock available.

Sony Ericsson C903 review: Slider-shot

Inspired by the Sony T-series point-and-shoot digcams with an elegant lens cover, the Sony Ericsson C903 is a compact and attractive cameraphone. The C903 is packed with features you'd expect of a high-end phone and it behaves like one as well. A GPS-enabled 5 MP slider with a nice large display, nifty feature-phone interface and friendly size is a welcome addition to the company portfolio. And yes, we think the Glamour Red version will be a favorite with the ladies.

The C903 official announcement served the humble purpose of warming the crowd up for the Sony Ericsson deployment at this year's MWC. Obviously no match for the Idou and Hikaru, the C903 simply completes the Cyber-shot lineup of the house featuring some welcome upgrades over the C902 like screen size and GPS. There's a distinctive design highlight too and the Sony T-series digicam back styling may as well be a strong selling point
•Quad-band GSM/GPRS/EDGE and dual-band HSDPA/ tri-band HSDPA in US version
•5 MP AF camera with dual LED flash, geo-tagging, face and smile detection, active lens cover
•Built-in GPS with A-GPS support, Wayfinder Navigator software, geotagging
•Dedicated camera mode switch and gallery keys
•Scratch resistant 2.4" 256K-color TFT display
•Backlit D-pad shortcuts in camera mode
•Accelerometer sensor for UI auto-rotate
•Bluetooth (with A2DP), USB v2.0
•FM radio with RDS and enhanced TrackID, YouTube client
•Threaded conversations in messaging
•Smart dialing