When a voice call is successfully placed, Twilio will assign it a unique ID that we refer to as a Call SID. A Call SID is an important troubleshooting resource to provide Twilio support when you report a voice-related issue.
You can find the SID for a call one of two ways:
1) By looking at the call log in your account portal:
Log into your Twilio account and navigate to Logs -> Calls, and click a call of interest to bring up the correct details.
The call SID is the first item displayed:
2) By making a REST API request to the Calls List Resource:
To find the SID for a specific call via the API, make a GET request to the call list resource. This will return a list of calls associated with your account along with details about each message.