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q731_1s.txt
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INTERNATIONAL TELECOMMUNICATION UNION
ITU-T RECOMMENDATION SUMMARY
Rec. No. : Q.731.1
Title : Stage 3 description for number identification supplementary
services using signalling system No. 7
Study Group : XI - Switching and Signalling
Version : New
Date of adoption : 1992
Notes :
DIRECT-DIALLING-IN (DDI)
Direct-Dialling-In (DDI) enables a user to call directly another user
on an ISPBX or other private system without attendant intervention,
the DDI digit(s) being the least significant digit(s) of the called
ISDN number.
The stage 1 definition of DDI is to be found in Recommendation I.251.
The stage 2 description is included in Recommendation Q.81.1. This
stage 3 description of DDI compliments the ISDN User Part (ISUP)
protocol as defined in Recommendations Q.761 to Q.764 and Q.766.
To order the complete text of this Recommendation, please use the
Order Form for ITU-T Recommendations. An electronic version of this
form is available on ITUDOC (Winword 2.0: UPI=ITU-5265; ASCII: UPI=ITU-2488).