Phone verification isn't an option available for all users on Upwork. Sometimes it's required and the team notifies the user about it. However, no badge will show on freelancer profile when it's done. It doesn't look like you were requested to complete phone verification at this time.
Thanks for the reply Valeria K. Yes you are right I was not requested to complete my phone verification but I just wanted to know that when and how phone verification is needed and completed. What if I want to verify my phone number without any request?
No, that's not correct. Upwork team may ask a user to do some additional verifications including phone verification. It is not requested by clients and it will not be displayed on profile.