UDP Packets from iPhone could not be captured in Charles Web Proxy Tool

Question

What i am doing ? I am testing an application installed on iphone device. In the application, a Voice Call happens over internet. I routed the traffic in my iphone device through the Charles web proxy tool installed in MAC machine using Proxy settings in device Settings -> WIFI option.

I turned WIFI on and started Charles in MAC machine. Now, i launched the application and clicked on the button to make a call. Call is established successfully. (I am in Network coverage area)

I Closed the charles in MAC machine. I launched Safari on iphone device and entered an URL. I get a message "No network available". But the Voice call is still continuing. I can hear the speaker at othe end even while this condition.

What is my assumption?

From this case, i understand that iphone device could not connect to internet.

What is my conclusion?

1. From this case, i understand that the Voice call which is happening over internet using UDP protocol will not be routed through Charles web proxy tool even if i set the proxy settings on the iphone device.

2. Charles web proxy tool can listen only to TCP connection.

What is my question?

1. My conclusion 1 and 2 is it correct?
2. If UDP packets can be monitored using Charles, how can i do it?

Answer 1

Setting the Proxy Settings on your iPhone (Or any device) only redirects web traffic (HTTP, HTTPS) to the proxy of your choosing. It will not redirect any other kind of traffic. To do that you will need to either configure the iPhone with a SOCKS proxy (Will redirect all traffic) or intercept the traffic elsewhere, such as at your wifi router.