INTERNATIONAL  TELECOMMUNICATION  UNION

		     ITU-T RECOMMENDATION SUMMARY


Rec. No. : T.563

Title :	Terminal characteristics for group 4 facsimile apparatus

Study Group : VIII - Terminals for Telematic Services

Version : Revised

Date of adoption : 1991

Notes :	


Group 4 facsimile apparatus is used mainly on public data networks 
(PDN) including circuit-switched, packet-switched, and the integrated 
services digital network (ISDN). The apparatus may be also used on the 
public switched telephone network (PSTN) where an appropriate 
modulation process will be utilized.

The procedures used with Group 4 facsimile apparatus enable it to 
transmit and reproduce image coded information essentially without 
transmission errors.

Group 4 facsimile apparatus has the means for reducing the redundant 
information in facsimile signals prior to transmission.

The basic image type of the Group 4 facsimile apparatus is black and 
white.

Other image types, e.g. grey scale image or colour image are for 
further study.

There are three classes of Group 4 facsimile terminals:

	-   Class I - Minimum requirement is a terminal able to send 
	    and receive documents containing facsimile encoded 
	    information (in accordance with Recommendation T.6, T.503 
	    and T.521).

	-   Class II - Minimum requirement is a terminal able to 
	    transmit documents which are facsimile encoded (in 
	    accordance with Recommendations T.6, T.503 and T.521). In 
	    addition, the terminal must be capable of receiving 
	    documents which are facsimile coded (in accordance with 
	    Recommendations T.6, T.503 and T.521). Teletex coded (in 
	    accordance with the basic coded character repertoire as 
	    defined in Recommendations T.60 and T.61), and also 
	    mixed-mode documents (in accordance with 
	    Recommendation T.561).

	-   Class III - Minimum requirement is a terminal which is 
	    capable of generating, transmitting and receiving 
	    facsimile coded documents (in accordance with the 
	    Recommendations T.6, T.503 and T.521), Teletex coded 
	    documents (in accordance with the basic coded character 
	    repertoire as defined in Recommendations T.60 and T.61), 
	    and mixed-mode documents (in accordance with 
	    Recommendation T.561).



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