A short video:
Go to 'Co-workers & Groups" page on the dashboard and then click on the "gear" icon right next to your (or whoever's) name
- A pop-up opens up. Enter the number. (Enter 0 followed by mobile number)
Once you have entered these details, you will find that your number is configured. Also to verify the newly added number, you need to place a missed call from this newly added number to 09513885656.
Now you can switch on and off this number based on your availability.