DECTEL Communications | WAN

Internet Access Equipment
There are many solutions for internet access depending on your company's needs for bandwidth and performance.

ISDN (128Kbps) (Integrated Services Digital Network) is probably the most common internet access type for small businesses. You will need to order the ISDN line from your local phone company and order service from an internet server provider. The most common router used for ISDN connectivity is the Ascend Pipeline. The higher end models of this line are capable of fractional T1 connectivity.

DSL (128 Kbps to 8 Mbs) (Digital Subscriber Line) is an emerging technology that has not been fully developed or utilized. There are currently two primary types of DSL access, aDSL and sDSL. The difference between the two is the upstream bandwidth. Since it is a newer technology there is no strong contender for routers in this market. However there is an Ascend model DSL router.

aDSL (Asymmetric Digital Subscriber Loop) provides a faster download rate than upload rate, this is done to maximize the download since most people simply need to download files and webpages from the internet. Typically the upstream data flow is between 16 and 640 kilobits per second while the downstream data flow is between 1.5 and 9 megabits per second. ADSL also provides a voice channel.

sDSL is made available to companies that need the capability to also send files as high speeds. It provides greater T1 access speeds (128 kb/s to over 8 Mb/s) at a fraction of the cost. However, sDSL is not widely available and is a newer technology.

Cable modem (512 Kbps to 52 Mbps) A cable modem is a device that enables you to hook up your PC to a local cable or RF TV line and receive data. The limitation however is that it is not capable of sending upstream data and you will have to purchase an isdn line or analog phone line to provide your upstream bandwidth, however the cost is not excessive.

DS1/T1 (1.544 Mbps) A T1 is an AT&T term for a digital carrier facility used to transmit a DS1 formatted digital signal at 1.544 megabits per second. A DS1 "frame" is composed of 24 eight-bit bytes (commonly from 24 DS0 sources, originally digitised voice-grade telephone signals), plus one framing bit (193 bits). 8000 bytes per second come from each source, and thus 8000 frames per second are transported by the DS1 signal. The result is 193*8000 = 1,544,000 bits per second. In order to get this service you will have to obtain a local loop from your telephone carrier, normally costing anywhere from $200-$800 and the connetion to your isp ranging from $500 to $2000 depending on the quality of the service. A common T1 router is the Cisco Systems 2500 Series router.