TDMA, CDMA and GSM?
TDMA, or Time Division Multiple Access, sorts messages into time slots in order to send them. Voice and data are converted to digital signals that are sent and received in bursts in specific time slots. CDMA, or Code Division Multiple Access, was developed by Qualcomm for military antijamming systems, which translates into highly private conversations. It spreads a low power signal across a wide frequency width, which provides for a significant increase in subscriber capacity. GSM, or Global System for Mobile Communications, was originally developed in Europe and works similarly to the TDMA system: it sorts messages into time slots. The unique feature of this technology is that it allows for a short message service, up to 124 characters, while simultaneously carrying voice traffic. For further information, please view our Digital Phone Technologies page.

Cellular vs PCS service?
The main difference is the bandwidth on which the two services operate. PCS operates on a 1.9 GHz bandwidth, while Cellular providers use 800 MHz. Furthermore, the Cellular 800 MHz bandwidth supports analog transmissions, unlike the 1.9 GHz. In most cases, however, PCS carriers will license bandwidth from cellular providers so that they can provide a fall back analog service. For further information, please view our Cellular Network overview page.

Can I browse the Web on my telephone?
There are some phones with a built-in Web browser. This allows you to view text-only versions of web pages on your phones screen. It can be useful if you are looking for a stock quote, want to keep up with the latest news, sports scores, etc. Of course, the technology is brand new and will develop over time. For further information, please visit our Wireless Web overview page.

What's the difference between text messaging and email services?
Email service is a type of text messaging. Many carriers will offer an email account that is something like yournumber@carriername.com. However, there are also other types of text messaging, such as operator assisted text messaging. This service allows someone to call in and leave a message with an operator who will then dispatch it in a textual format to your phone. The third type of text messaging is phone-to-phone text messaging. You can use your phone's keypad to send messages to other people on your network. You push "2" for "A" and push "2, 2" for "B", etc. The majority of the time, this type of text messaging is only available for people on similar networks.

How does the two-way radio function work on a telephone?
The two-way radio function on a telephone is currently only available from Nextel. It uses Specialized Mobile Radio (SMR) to facilitate a one-to-many or many-to-one dispatch service. It is called the Nextel Direct Connect feature and is superior to a walkie-talkie because of its range. Converse with people up to 75 miles away with complete privacy.

Are cell phones really dangerous?
Today's major medical studies have not shown any conclusive evidence that cell phones are dangerous to humans. For further details, see our cell phone radiation page.