1.20 Integrated Services Digital Network (ISDN) Service FeaturesFeature Guide 1971.20.1.10 Completion of Calls to Busy Subscriber (CCBS)DescriptionIf the called party is busy and the call has been made using an ISDN line, an extension usercan set to receive callback ringing when the called party becomes free. When the user answersthe callback ringing, that party’s number is automatically dialled.This feature complies with the following European Telecommunication Standard (ETS)specifications: ETS 300 359 Completion of Calls to Busy Subscriber (CCBS) supplementaryservice.Conditions• This feature is available under the following conditions:a) The caller’s PBX is capable of using CCBS and the service is provided by the network.b) The called party’s PBX is capable of accepting CCBS.• To receive and send CCBS, receiving and sending CCBS must be enabled individually onan ISDN port basis through system programming.• An extension user can set only one CCBS. The last setting is effective.• The CCBS setting is cancelled if there is no callback ringing within 60 minutes or callbackringing is not answered within 10 seconds.• If an extension user makes a call using the CCBS feature, the preassigned CLIP numberfor the extension will be used even though the extension has set CLIR or the extension hasused the CLIP for the incoming call distribution group by pressing the ICD Group buttonwhen the CCBS has set. ( 1.20.1.2 Calling/Connected Line Identification Presentation(CLIP/COLP))• After using the CCBS feature, using Last Number Redial will not retrieve the numberdialled by CCBS. ( 1.6.1.4 Last Number Redial)• An extension user that has set the CCBS feature cannot receive callback ringing while theextension is holding a call.User Manual ReferencesUser Manual1.2.4 When the Dialled Line is Busy or There is No Answer
