Carrier Technology
Description
Speed
Physical Medium
Comments
Dial-up Access On demand access using a modem and regular telephone line. 2400 bps to 56 Kbps Twisted pair (regular phone lines)

  • Cheap but slow compared with other technologies.

  • Speed may degrade due to the amount of line noise.
ISDN Dedicated telephone line and router required. 64 Kbps to 128 Kbps Twisted pair
  • An ISDN line costs slightly more than a regular telephone line.
Cable Special cable modem and cable line required. 512 Kbps to 10 Mbps Coaxial cable; in some cases telephone lines used for upstream requests.
  • Must have existing cable access in area.
  • Cost of bring service into an area and trenching cable can be prohibitive.
  • Networkable
ADSL

Asymmetric Digital Subscriber Line

 This new technology uses the unused digital portion of a regular copper telephone line to transmit and receive information. ADSL is asymmetric since it receives at 6 to 8 Mbps per second but can only send data at 64 Kbps.

A special modem and adapter card are required.

 512 Kbps to 8 Mbps Twisted pair (used as a digital, broadband medium)
  • Doesn’t interfere with normal telephone use.
  • Bandwidth is dedicated not shared like with cable.
  • Bandwidth is affected by the distance from the network hubs. Must be within 5 km (3.1 miles) of telephone company switch.
  • Not networkable
Wireless (LMCS) Access is gained by connection to a high speed cellular like local multi-point communications system (LMCS) network via wireless transmitter/receiver. 2 Mbps or more Airwaves

Requires outside antenna.
  • Still in the early test stages.
  • In theory its capable of super speeds of 10 mbps or more.
  • Can be used for high speed data, broadcast TV and wireless telephone service.
Satellite The computer sends request for information to an ISP via normal phone dial-up communications and data is returned via high speed satellite to rooftop dish, which relays it to the computer via a decoder box. 400 Kbps Airwaves

Requires outside antenna.
  • Bandwidth is not shared.
  • Satellite companies are set to join the fray soon which could lead to integrated TV and Internet service using the same equipment and WebTV like integrated services
  • Service is one way with a slow uplink speed.
  • Requires an Internet service account.
  • Phone line is busy while online.
Frame Relay Provides a type of "party line" connection to the Internet.

Requires a FRAD (Frame Relay Access Device) similar to a modem, or a DSU/CSU.

 56 Kbps to 1.544 Mbps Various
  • May cost less than ISDN in some locations.
Fractional T1

(Flexible DS1)

 Only a portion of the 23 channels available in a T1 line is actually used. 64 Kbps to 1.544 Mbps Twisted-pair or coaxial cable
  • Cheaper than a full T1 line with growth options of 56 Kbps or 64 Kbps increments as required.
T1 Special lines and equipment (DSU/CSU and router) required. 1.544 Mbps Twisted-pair, coaxial cable, or optical fiber
  • Typically used for high bandwidth demands such as videoconferencing and heavy graphic file transfers. Many large businesses and ISP use T1.
  • Expensive
T3 Typically used for ISP to Internet infrastructure. 44.736 Mbps Optical fiber
  • Very large bandwidth
  • Extremely expensive and complex
OC-1 Typically used for ISP to Internet infrastructure within Internet infrastructure. 51.84 Mbps Optical fiber  
OC-3 Typically used for large company backbone or Internet backbone. 155.52 Mbps Optical fiber