func CurrentCall(ctx context.Context) IncomingCall {
	if params := getTChannelParams(ctx); params != nil {
		return params.call
	}
	return nil
}
func CurrentCall(ctx context.Context) IncomingCall {
	if params := getTChannelParams(ctx); params != nil {
		return params.call
	}
	return nil
}
// CurrentCall returns the current incoming call, or nil if this is not an incoming call context.