How To Verify The Phone Number Similar To Whatsapp?

Can anyone please tell me how to verify the phone number. Once you've installed the app, some random code will be generated and sent as a text message to your phone. Then you ente

Solution 1:

There are different services for things like this. They require a server and using some sort of service like Twilio and Nexmo.

Solution 2:

Should be a 3rd party service.

It works as below steps which is kind of straight forward:

1. Mobile App sends a request to 3rd party service. That service trigger a SMS carrying a 'code' to user's phone (you have asked user to type in the phone no. prior), as well as return a 'token' to Mobile App.
2. After user getting the SMS and type in the code, Mobile App send the 'code' and the 'token' to 3rd party service.
3. 3rd party verify the 'code' and 'token' based on their database.

One service we ever used is: http://www.openmarket.com/messaging/sms-messaging/