@Pranav Satija, Thanks for posting in Q&A. Based on my researching, I find a link describe the following commands to get the Phone number information:
Get-MgUser -All:$true -PipelineVariable user | ForEach-Object { Get-MgUserAuthenticationPhoneMethod -UserId $user.UserPrincipalName | Select-Object @{ N='UserPrincipalName'; E={ $user.UserPrincipalName }}, ID, PhoneNumber, PhoneType}
You can try it. Hope the above command can help.
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