protected static function get_hold_channels($channels)
    {
        $ichannels = array();
        foreach ($channels as $channel) {
            if (is_string($channel)) {
                $channel = new Channel($channel);
            }
            $ichannel = array();
            $ichannel['name'] = $channel->name;
            if (!is_null($channel->prev_id)) {
                $ichannel['prev-id'] = $channel->prev_id;
            }
            $ichannels[] = $ichannel;
        }
        return $ichannels;
    }