A.1 MSs which do not support CCBS

24.0933GPPCompletion of Calls to Busy Subscriber (CCBS)Release 17Stage 3TS

MSs which do not explicitly support CCBS are not precluded from attempting to activate CCBS or from accepting a CCBS Recall. The mechanisms employed to offer the CCBS service to these MSs shall be a matter for individual networks.

A.1.1 Activation for non-supporting MSs

The network shall send DISCONNECT to MS A (cause #17 or #34) with diagnostic field indicating CCBS is Possible, and a progress indicator indicating inband information is available. This inband information shall be used to indicate CCBS possible. The absence of a progress indicator in the DISCONNECT, prevents subscriber A from successfully activating CCBS. If subscriber A requests CCBS, MS A will send a REGISTER message, containing a ProcessUnstructuredSS-Request invoke component. The receiving network entity shall pass the data received in the request to the application handling USSD operations and shall wait for the response of the application. When the application accepts the request and terminates the dialogue, the network shall clear the transaction by sending a RELEASE COMPLETE message containing a return result component.

If the network is unable to process the request received from the MS, it shall clear the call independent transaction by sending a RELEASE COMPLETE message containing a return error component.

When the call independent transaction has been cleared, either the MS or the network shall release the call related transaction by sending a RELEASE COMPLETE message.

MS A NETWORK DISCONNECT (PD = CC) <———————————————————————————————————————————— (Cause = #17 or 34, Diagnostic = CCBS Possible) Progress Indicator = #8

REGISTER (PD = SS) ————————————————————————————————————————————> Facility (Invoke = ProcessUnstructuredSS-Request (ussd-DataCodingScheme, ussd-String))

RELEASE COMPLETE (PD = SS) <———————————————————————————————————————————— Facility (Return Result = ProcessUnstructuredSS-Request (ussd-DataCodingScheme, ussd-String))

RELEASE COMPLETE (PD = SS) <———————————————————————————————————————————— Facility (Return Error = ProcessUnstructuredSS-Request (ussd-DataCodingScheme, ussd-String))

RELEASE COMPLETE (PD = SS) < – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – Facility (Return Error (Error))

RELEASE COMPLETE (PD = SS) < – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – Facility (Reject (Invoke_Problem))

RELEASE (PD = CC) (Note1) – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – >

RELEASE COMPLETE (PD = CC) < – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –

RELEASE (PD = CC) (Note 2) < – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –

RELEASE COMPLETE (PD = CC) – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – >

Figure A.1: Activation of CCBS for non supporting MSs

NOTE 1: If Subscriber A rejects the CCBS Possible indication or ends the call having received either a successful or unsuccessful indication following an activation attempt, then the MS shall send a RELEASE message.

NOTE 2: If the call control timer expires (T306) or if T1 expires, then network shall send a RELEASE message to MS.