To initiate a new outgoing phone call we need to specify three parameters:
Lets take a look at these parameters in a little more detail.
The 'From' parameter must be set to one of your Twilio Numbers or to a phone number that you have verified with Twilio.
If you don't have a Twilio Number yet or you want to use a different number for the caller ID, you can verify a number on the Phone Numbers page.
The 'To' parameter is the phone number you wish to call. It should be
formatted with a '+' and country code e.g.,
+16175551212. '1' is the
international country code for the US and Canada, and the '+' formats the
number in E.164, the phone number standard used by Twilio.
The final parameter is the HTTP URL of the TwiML file that Twilio will fetch when the call is answered.