Go to your Google Cloud console and enable IAM Service Account Credentials API
Add a role Service Account Token Creator in App Engine default service account.
1. First you need to create account in https://login.twilio.com
2. Then fill documents
3. Then Press on Create Verify Service button
4. Then you got demo number. Now click on Next button.
5. Then go Messaging > Content Template Builder then create your first content template
6. Then fill Template Name , Template Language and select content type
7. Then fill configure content Text and press on Save button
8. Then you can check your Content Template
9. Then go Services > and Create Messaging Services
10. Then fill Messaging Service friendly name and Messaging for
11. Then Press on Add Senders Button .
12. Then Select Phone Number
13. Then Press on Step 3: Set up integration and Complete Messaging Services Setup
14. Then go Send an SMS section and copy Api Url
15. Now go Account > API keys & tokens
16. Then copy Account SID and Auth token
17. Now search Basic Auth Header Generator on Google and then fill Account SID as Username and Auth token as Password and generate the Basic Auth header
18. Then go your Web > Settings > SMS Settings section
a.Copy the Api Url from https://console.twilio.com/ > Try it out > Send an SMS section > check the 14. No. point
b. Then fill METHOD section as POST
c. Then fill the Authorization section check the 17. No. Point
d. Now fill Content-Type this application/x-www-form-urlencoded
e. Fill the body check the screenshot Body= {otp}Enter Your body.&From=Enter sender mobile number&To={mobile}
e. Then Enable Custom Mobile OTP make True
