21 Interactions with SCUDIF call

22.0783GPPCustomised Applications for Mobile network Enhanced Logic (CAMEL)Release 17Service descriptionStage 1TS

Refer to 3GPP TS 23.172 [14] for a definition of "preferred service", "less preferred", "service selected " and "fallback".

21.1 Call Party Handling

The CSE may invoke CPH procedures only if one of the following conditions is fulfilled:

– during call establishment, the preferred service is speech. After the VPLMN/IPLMN has completed the CPH procedure, the VPLMN/IPLMN shall force a fallback to speech; or

– during the active phase of the call, the selected service is speech. After the VPLMN/IPLMN has completed the CPH procedure, the VPLMN/IPLMN shall force a fallback to speech.

21.2 User Interaction

The CSE may initiate user interaction or order in-band tone only if one of the following conditions is fulfilled:

– during call establishment, the preferred service is speech; or

– during the active phase of the call, the selected service is speech.

21.3 User-requested service change

The VPLMN/IPLMN shall disallow a user request for service change during user interaction.

If the user request for service change occurs during the playing of a CAMEL warning tone, then the playing of the CAMEL warning tone shall be stopped.

21.4 CAMEL warning tones

21.4.1 Warning tone related to call duration control

For a SCUDIF call the CAMEL warning tone may be ordered by the CSE. At the time of tone connection, the VPLMN/IPLMN shall not connect the tone if the selected service is multi media.

21.4.2 Warning tone related to tone injection

The CSE shall be able to inject a warning tone if the selected service is speech, but not if the selected service is multi media.

21.5 Mid-call procedure

The CSE shall be able to arm the mid-call event when the selected/preferred service is either speech or multi media.

21.6 Follow-on call

If the CSE creates a follow-on call before the call has reached the active phase, then the VPLMN/IPLMN shall establish the follow-on call with the preferred service and the less preferred service that were available during call establishment.

If the CSE creates a follow-on call after the call has reached the active phase, then the VPLMN/IPLMN shall establish the follow-on call with the selected service and the not-active service that were available during the active phase of the call.

21.7 Service initiation at unsuccessful call establishment

If an initial service event occurs due to unsuccessful call establishment, then the VPLMN/IPLMN shall report to the CSE, the preferred service and the less preferred service that were available during call establishment.