Digital Technologies: PCS, TDMA, CDMA and GSM

It's important to note that while there is one standard for analog technology, there are different variations on digital technology. These variations are primarily based on the way information is transmitted. The most common digital technologies include:

• PCS (Personal Communication System)
• Offers advanced features and sound quality
• Coverage only available in some parts of the country
• Often offered by national cellular carriers with nationwide rate plans
• Requires a PCS phone
  
  TDMA (Time Division Multiple Access)
• One of the most common digital communication technologies. It divides a sequence of conversations into packets of data according to time.
• Offered in several bandwidths, typically 800 MHz and1900 MHz
• Requires a TDMA phone
  
  CDMA (Code Division Multiple Access)
• Another popular digital technology that separates communications by code
• Also offered in several bandwidths, typically 800MHz and 1900 MHz
• Requires a CDMA phone
  
  GSM (Global System for Mobile Communication )
• The most widely used digital technology in Europe, Middle East, and Asia.
• A rapidly expanding technology in North America.
• Offered in 1900 MHz in the US, Canada and Latin America. Also offered in 900 MHz in parts of Latin America.
  
  Different service providers in the same region may use different digital technologies, thus, a phone that works on one type of digital network may not work on another. It's important to always check that compatible service for a wireless phone is available in your area before you buy it.

Digital Vs Analog

Here's a quick overview of the two common wireless technologies available in the United States.

Analog

The first cellular networks, introduced in the early 1980s, were built on analog technology. Analog networks were rapidly deployed throughout the country, providing coverage from almost any calling area within the United States. The following are characteristics of analog technology:

• The earliest and mostly widely used cellular technology
• Still popular for basic service
• Its extensive network has made it popular as a backup service available with dual-mode phones since analog offers coverage in some areas without digital coverage
• Phones are typically less expensive than digital phones
  
  Digital
  
  As cellular technology evolved, digital technology entered the scene. Digital technology transmits signals and data differently than analog technology, allowing for more efficient transmissions and enhanced sound quality. Digital technology also enables additional calling services. However, because these newer digital networks are still being built, they do not yet match the breadth of coverage of analog networks. This is one reason behind the proliferation of dual-mode phones, which offer digital service where available, and analog service as a backup when digital is not available. Following are characteristics of digital technology:
  
• Newer technology offers a wide range of features from call waiting to e-mail access and more
• Digital service costs less to provide, offers high quality sound and is less draining on battery life
• Digital phones offer lots of features, from display screens to e-messaging capabilities, but typically cost more to make
• Network coverage is not yet as extensive as the analog network. Dual mode phones can switch between analog and digital technology.
• For even greater coverage flexibility, digital dual-band phones can operate on two different bandwidths or frequencies—800 MHz and 1900 MHz