Introduction To Line Telecommunications


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9. Simple Telephone Devices
  9. - Simple Telephone Devices 9.4 - Modems
  9.1 - Telephone Answering Machines 9.5 - Voicemail Systems
  9.2 - Cordless Telephones 9.6 - Specialist Devices
9.3 - Facsimile Machines

9.3 - Facsimile Machines

A Facsimile (FAX) machine is a device to copy a document and send the image, or facsimile, across the network to a similar device at the receiving end, where a copy is reproduced onto paper or into a PC. Sending documents in this way is quicker than postal services and since pictures can also be sent more efficient than verbal descriptions. This saves time and money as the information transfer is immediate and action can be taken on the document in all but the most sensitive circumstances when originals are required. In recent time Fax and now email have become the preferred means of communication in business, after the telephone.

The document is scanned and digitised to become a bitstream (series of 0’s and 1’s) which is then encoded and control information added for transmission across the network using a modem. At the receiving end the control information is used to recreate a copy of original document. The scanning and encoding may be performed live once a connection between the two machines is established, which is why documents are sent in sections, each is coded transmitted and reception confirmed before the next part is sent.

FAX equipment is divided into groups depending upon its type. In general terms these are Group 4, digital (I.431) able to connect directly to the digital network; Group 3 the current standard for connection to the analogue network and the older groups 1 and 2, now discontinued, for the analogue network. Group 4 can communicate with Group 3 machines; Group 3 can communicate with some Group 2 of which there are still some in service; Group 1 can only communicate with other Group 1 machines.

Common FAX features include:

Copy The ability to scan and copy locally, doubling as a light use photocopier.
Broadcast The same document can be stored and sent to multiple destinations automatically.
Memory Dial Frequently used numbers can be stored and dialled using abbreviated codes.
Memory Store Received documents are held in the machine memory if the paper runs out.
PC Transfer Received faxes are transferred to a PC or office network for on screen viewing
Print / Scan The fax machine doubles as a printer / scanner for a connected PC





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Extracted from

Introduction To Line Telecommunications
Copyright Panasonic Business Systems UK Ltd 2000