In a conventional telephone system, the caller is connected to the person he wants to talk to by switches at various telephone exchanges. The switches form an electrical connection between the two users and the setting of these switches is determined electronically when the caller dials the number. Once the connection is made, the caller's voice is transformed to an electrical signal using a small microphone in the caller's handset. This electrical signal is then sent through the network to the user at the other end where it transformed back into sound by a small speaker in that person's handset. There is a separate electrical connection that works in reverse, allowing the users to converse.

Mobile Communication

Mobile phones have had a significant impact on telephone networks. Mobile phone subscriptions now outnumber fixed-line subscriptions in many markets. Sales of mobile phones almost equally shared amongst the markets of Asia/Pacific, Western Europe, CEMEA Central Europe, the Middle East and Africa , North America and Latin America In terms of new subscriptions over the five years from 1999, Africa has outpaced other markets with 58.2% growth. Increasingly these phones are being serviced by systems where the voice content is transmitted digitally such as GSM or W-CDMA with many markets choosing to depreciate analogue systems such as AMPS.

In fewer than twenty years, mobile phones have gone from being rare and expensive pieces of equipment used primarily by the business elite, to a pervasive low-cost personal item. In many countries, mobile phones now outnumber land-line telephones, with most adults and many children now owning mobile phones. In the United States, 50% of children own mobile phones. It is not uncommon for young adults to simply own a mobile phone instead of a land-line for their residence. In some developing countries, where there is little existing fixed-line infrastructure, the mobile phone has become widespread.

Star Phone Cards:
We are Provided Cheap Calls To India with vary cheapest rate for save mony of Prepaid Calling Cards for international and domestic calls.We have the largest selection of UK phone cards and International calling cards available on the internet. The cards will save you pounds on the cost of international phone calls from www.starphonecards.co.uk.

Digi Calling Cards:
We offer a fantastic range of Calling Cards, delivered to you instantly. Find great prepaid calling cards, Pakistan Prepaid Calling Cards and instant phone card rates to all destinations and save money from www.digicallingcards.com.

SpeedyPin:Purchase pre paid phone cards over the internet and make calls immediately from www.pinspeedy.com. Find the cheap long Discount Phone Cards with our offer a wide range of international phone cards at the best rates. The international prepaid phone card find cheapest reliable Discount Phone Cards.