Freeswitch: How to determine if call was answered when bridging an inbound and outbound call?

Question

In this implementation, I'm trying to do call patching between an inbound call and a outbound call via the session.bridge() command.

I have already received the inbound call and my Python script is playing. In this script I'm trying to patch the running call with the numbers in the number_list(list of numbers) one by one until the list is exhausted or till the call is patched and answered.

My Code:

for cp_num in connObj.cp_list:
    ivr_log.debug("Attempting to dial Call Patch Number:%s"%(cp_num['cp_no']))
    connObj.patch_uuid = uuid.uuid1()
    cmd_str = """{ignore_early_media=true,execute_on_answer=record_session %s/%s_%s.wav,origination_uuid=%s,originate_timeout=45,script_name=gaadi_test}freetdm/wp4/a/%s"""%(connObj.recording_path,connObj.uuid,connObj.caller_id,connObj.patch_uuid,cp_num['cp_no'])
    connObj.bridge(cmd_str) #BRIDGE
    connObj.hangup_cause = connObj.getVar("last_bridge_hangup_cause")
    if connObj.hangup_cause in ['NORMAL_CLEARING', '']:
        connObj.cp_status = "SUCCESS"
        return True
connObj.cp_status = "FAILED"
connObj.playback(connObj.path_sound + 'all_reps_busy.wav')
return False

Multiple numbers to the bridge command for sequential dialing. From freeswitch documentation: Multiple endpoints sequential -- no limit to failover number

bridge <target_endpoint>[|<target_endpoint>]

My Implementation

cmd1 = """{ignore_early_media=true,originate_timeout=45}[origination_uuid=%s,script_name=gaadi_test]freetdm/wp4/a/%s"""%(connObj.patch_uuid1,connObj.cp_list[0]['cp_no'])
cmd2 = """[origination_uuid=%s,script_name=gaadi_test]freetdm/wp4/a/%s"""%(connObj.patch_uuid2,connObj.cp_list[1]['cp_no'])
cmd = "%s[|%s]"%(cmd3,cmd4)
ivr_log.debug("CMD=%s"%(cmd))
connObj.call_patch_start_time = int(time.time())
connObj.patch_start_datetime = datetime.datetime.now().strftime("%Y-%m-%d %H:%M:%S")
connObj.bridge(cmd)

PS: ConnObj.bridge(cmd) is working perfect for only one target point.

Sequential Dialing solution: just a little changes in cmd1 and cmd2. I have not confirmed if the origination uuid will be different for both the calls.

cmd1 = """{ignore_early_media=true,originate_timeout=45,script_name=gaadi_test}[origination_uuid=%s]freetdm/wp4/a/%s"""%(connObj.patch_uuid1,connObj.cp_list[0]['cp_no'])
cmd2 = """[origination_uuid=%s]freetdm/wp4/a/%s"""%(connObj.patch_uuid2,connObj.cp_list[1]['cp_no'])
cmd="%s|%s" #removed the brackets and its working now.
connObj.bridge(cmd)

EDIT:

Finally I solved the problem with Stanislav's approach. I used api_on_answer. On answer I wrote a file on the disk and then checked whether the file was present or not. If the file was present then the call was answered.

Answer 1

You can set execute_on_answer variable to execute a hangup:

https://wiki.freeswitch.org/wiki/Variable_execute_on_answer

But in general, mod_python is not the right place for such tasks: the script is executed as a thread inside FreeSWITCH process, and you don;t have any control while a freeSWITCH application is being executed (bridge in your case). A much better option is to use the event socket library (ESL), and then you can control the call flow asynchronously and receive events that are relevant to call state changes.