Voicemail Server Audio Encoder Negotiation

The voice mail server determines the audio encoder type (WB or NB) of the subscriber's terminal in advance, before the message depositing user arrives. This preliminary identification allows the server to prepare the appropriate encoding format ahead of time, avoiding the need for real-time transcoding when the message is deposited. The server stores messages in the predetermined format that matches the subscriber's terminal capabilities, thus eliminating or reducing processing resource demands during actual message deposition.

The server performs encoder determination and message encoding in advance, before the message is actually needed. By preparing the message in the correct format beforehand, the system avoids real-time transcoding operations that could introduce audio quality degradation. The message is stored in a format that is predetermined to be compatible with the subscriber's terminal, ensuring audio quality is preserved without requiring risky real-time conversion.

The voice mail server dynamically changes the encoding parameter (frequency band width) based on the determined capabilities of the subscriber's terminal. If the terminal supports WB encoding, the server stores messages in WB format to preserve audio quality. If the terminal only supports NB encoding, the server stores messages in NB format to ensure compatibility. This parameter adaptation resolves the contradiction between audio quality and terminal compatibility.

The voice mail server uses feedback from the subscriber's terminal regarding its audio encoder capabilities (WB or NB support) to determine the appropriate encoding format. The terminal provides information about its supported codecs, and the server uses this feedback to make an informed decision about message encoding. This feedback mechanism simplifies the overall system by using existing capability information rather than requiring complex real-time transcoding infrastructure.