3Com AccessBuilder 500 User Manual - page 22

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The most modern and efficient of these WAN services includes ISDN 

(Integrated Services Digital Network). This provides a high speed dialup 

facility to allow your AccessBuilder 500 to automatically and quickly dial 

remote offices, transmit your data between remote PCs just as speedily 

and then disconnect the call. You incur minimum ISDN telephone charges 

as calls are made only when needed. This is known as Dial on Demand.

ISDN can also be used to make voice calls using the AccessBuilder 500’s 

Voice port. You can connect an ordinary telephone handset, faxes and 

other similar office equipment. 

The AccessBuilder 500 also has al port for connection over a permanent 

leased line WAN connection, also available from your telephone carrier 

organization. Leased lines are available to work at a range of speeds 

which incur higher costs the higher the line speed. The benefit of 

leased lines is their permanenc

e

 and fixed cost. No dialling is required 

but unlike ISDN you pay a fixed cost regardless of whether you transfer 

little data or high volumes of data 24 hours a day.

Overall ISDN is probably the most cost effective solution for small 

businesses. However, if your requirements to move data between sites 

is likely to increase, the flexibility offered by the AccessBuilder 500 fitted 

with both ISDN and WAN ports allows you to choose the type of 

connection between sites that best meets your needs.

Typically, the AccessBuilder 500 is used to interconnect LANs running 

protocols such as Transmission Control Protocol/Internet Protocol 

(TCP/IP) or Novell Internetwork Packet Exchange (IPX). Offering full 

LAN-to-LAN connectivity at speeds up to 64 Kilobits per second (Kbps) 

on each ISDN B channel (128 Kpbs in total) and up to 2 Megabits per 

second (Mbps) on the WAN port, the AccessBuilder 500 is a compact 

desktop unit with unrivalled price and performance.

In the USA, some ISDN services run over 56 Kbps channels. Basic Rate 

ISDN therefore offers connectivity of 112 Kbps in total.