/**
 * Delegate for {@link SimpleUser}.
 * @public
 */
export interface SimpleUserDelegate {
    /**
     * Called when a call is answered.
     * @remarks
     * Callback for handling establishment of a new Session.
     */
    onCallAnswered?(): void;
    /**
     * Called when a call is created.
     * @remarks
     * Callback for handling the creation of a new Session.
     */
    onCallCreated?(): void;
    /**
     * Called when a call is received.
     * @remarks
     * Callback for handling incoming INVITE requests.
     * The callback must either accept or reject the incoming call by calling `answer()` or `decline()` respectively.
     */
    onCallReceived?(): void;
    /**
     * Called when a call is hung up.
     * @remarks
     * Callback for handling termination of a Session.
     */
    onCallHangup?(): void;
    /**
     * Called when a call is put on hold or taken off hold.
     * @remarks
     * Callback for handling re-INVITE responses.
     */
    onCallHold?(held: boolean): void;
    /**
     * Called when a call receives an incoming DTMF tone.
     * @remarks
     * Callback for handling an incoming INFO request with content type application/dtmf-relay.
     */
    onCallDTMFReceived?(tone: string, duration: number): void;
    /**
     * Called upon receiving a message.
     * @remarks
     * Callback for handling incoming MESSAGE requests.
     * @param message - The message received.
     */
    onMessageReceived?(message: string): void;
    /**
     * Called when user is registered to received calls.
     */
    onRegistered?(): void;
    /**
     * Called when user is no longer registered to received calls.
     */
    onUnregistered?(): void;
    /**
     * Called when user is connected to server.
     * @remarks
     * Callback for handling user becomes connected.
     */
    onServerConnect?(): void;
    /**
     * Called when user is no longer connected.
     * @remarks
     * Callback for handling user becomes disconnected.
     *
     * @param error - An Error if server caused the disconnect. Otherwise undefined.
     */
    onServerDisconnect?(error?: Error): void;
}