修改switch_ivr_bridge.c 

static switch_status_t audio_bridge_on_exchange_media(switch_core_session_t *session)

中的：

if (switch_channel_test_flag(channel, CF_ANSWERED)&&switch_true(switch_channel_get_variable(channel,SWITCH_HANGUP_AFTER_BRIDGE_VARIABLE))) {

                                        switch_channel_hangup(channel, SWITCH_CAUSE_NORMAL_CLEARING);

                                        //switch_channel_hangup(channel, SWITCH_CAUSE_ORIGINATOR_CANCEL);

                                } else {

                                        //switch_channel_hangup(channel, SWITCH_CAUSE_NORMAL_CLEARING);

                                }

和

if (switch_channel_get_state(channel) == CS_EXCHANGE_MEDIA) {

                switch_channel_set_variable(channel, "park_timeout", "72000");//改为park 20小时

                switch_channel_set_state(channel, CS_PARK);

        }

摘自 百问freeswitch第三版  第210题