Here in this you are going to see how whatsapp will work when given a already registered mobile number in the verification process.
For this,you need to have two mobiles with SIM inserted and with minimum balance.
In these mobiles,mobile B is already registered with whatsapp and mobile A installed but not registered.
Now just follow the steps to verify:
1. Install the application in mobile A.
2. Launch the application.
3. Enter the mobile B mobile number and tap on “OK” button.
4. Again after 5 minutes,mobile B will receive a message from Whatsapp server which contains 6 digits code.
5. After the total time(10 minutes),Displays a popup showing “SMS verification has failed,continue voice verification by calling the entered number”.
6. After tapping on “call me” button,again a popup appears with “Enter code here” field.
7. As soon as we tap on “call me” button, a call from Whatsapp server will come to the entered number.
8. This call will continue till we attend the call.
9. If the call was answered,a 6 digit number will be heard by voice.
10. If we enter the 6 digits code which was heard,the mobile A gets registered with the entered number and call gets automatically disconnected.
11. Otherwise if we enter the 6 digits code which was received as an SMS, the mobile A gets registered with the entered number.i,e. mobile B mobile number.
12. Then mobile B will gets “connection failed,reverify” popup.
This will happen because whatsapp will work for one number and one device.
If any one try to register with already registered number,a highly secured procedure is implemented which will protect the user from unauthorised persons.
Understanding WhatsApp 