speedtocontact.log

On 8th:
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Phone: 19375949377

1st call attempt: 2016-04-08 09:35:36 (PDT)  doesn't reach our server (phone.plivo.com)

Re-try after 14 seconds
2nd call: 2016-04-08 09:36:50 (PDT) reaches our server after 1 second 
@ Apr  8 16:36:51 (Time mark in UTC) - [email protected] from IP: 72.69.27.74:58035 TO [email protected]
@ Apr  8 16:37:05 (Time mark in UTC) - Call answered by the destination end
@ Apr  8 16:37:09 (Time mark in UTC) - BYE from webRTC client after 4 secs the call is answered 


On 7th 
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Phone:14847649077

1st call: 2016-04-07 16:35:52 (PDT) - this call doesn't reach our server (phone.plivo.com)

Re-try after 4 seconds

2nd call: 2016-04-08 16:35:56 (PDT) - Call reaches our server after 2 seconds 
@ Apr  7 23:35:58 (Time mark in UTC) - FROM [email protected] from IP: 65.175.49.180:21447 TO [email protected]
@ Apr  7 23:36:03 (Time mark in UTC) - Call answered by the destination end
@ Apr  7 23:36:04 (Time mark in UTC) - BYE from the webRTC client after 1 second the call is answered 


On 6th 
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Phone:12298549301

1st call: 2016-04-06 12:11:14 - this call doesn't reach our server (phone.plivo.com)


Re-try after 5 seconds 

2nd call: 2016-04-06 12:11:19 (PDT) - Call reaches our server after 1 second 

@ Apr  6 19:11:20 (Time mark in UTC) - FROM [email protected] from IP: 65.175.49.180:25956 TO [email protected]
@ Apr  6 19:11:32 (Time mark in UTC) - Call is answered by the destination
@ Apr  6 19:16:59 (Time mark in UTC) - BYE from the webRTC client after 27 seconds the call is answered 


Analysis:

The 1st call never reaches our server (phone.plivo.com), one of the reason that I can think of would be websocket connection is closed
That's why there's no API ping to his application in the ANSWER_URL

If the session is failed, then the console logs will show

WebSocket connection to 'wss://phone.plivo.com:5063/' failed: Establishing a tunnel via proxy server failed.
plivo.min.js:5 PlivoWebSDK | 21:17:28.105 | websocket connection closed

If the session is successfully established, the console logs would look like this: 

PlivoWebSDK | 23:28:49.419 | plivojs:_onNewSession
phone.html:219 get media permission
phone.html:127 onCalling
plivo.min.js:5 PlivoWebSDK | 23:28:52.797 | plivojs_onOutCallProgress
plivo.min.js:5 PlivoWebSDK | 23:28:52.823 | plivojs_onOutCallProgress
plivo.min.js:5 PlivoWebSDK | 23:28:55.900 | plivojs:onCallStarted

We need to watch for events like onNewSession, onOutCallProgress and onCallStarted
Or he can place webhooks in these events, and keep a watch whether these events are triggered or not.

With respect to the call hangup from the webRTC client, I think the web application is invoking the method: Plivo.conn.hangup()
This will delete the existing call dialog session, terminate the RTC session and BYE message will be sent out from the webRTC client 

Here, the console logs would be

PlivoWebSDK | 23:48:25.790 | onCallEnded
phone.html:142 onCallTerminated

We need to watch for onCallEnded event

So, we would definitely need console logs from his end for failed attempts and disconnects.