It seems your connection doesn’t support early media you might need Progress for that. Playback, by default, answers the call.
Also Before running any application that has sound playback (Playback, Background, VoiceMailMain2, etc.) it would be wise to execute an Answer first.
Also, you should not be tempted to avoid call charging all together by playing prompts and not answering the call. Telcos will generally not connect 2-way audio until you answer, and in any case will view this as not “playing fair” with them, subjecting you to service disconnection.
I checked those but I want to pay a message to the caller first because my system deals with overseas calls and don’t want user to waste money just for hearing those message.