Azure AD Connect - Need to sync custom phone number to Azure "Business Phone" attribute for Teams Calling

Question

Hello, short story long - we are Azure hybrid AD joined and as such, can't edit user properties in Azure AD. We are left to use Azure AD Connect to propagate Active Directory properties to Azure. That's all good. Now switching to Teams, Teams allows extension dialing but uses only the Azure "Business Phone" property to to get the phone number and the extension. This telephone and extension format is "+13215551212;ext=1234". I need to understand how I go about finding an on-prem attribute that I can add this telephone+extension, such that it winds up in the "Business Phone" Azure field after a.
I've already enabled "Directory extension attribute sync" but still can't figure out how to get values to the Azure filed mentioned. I'm fairly certain that the only way to achieve this is by using Azure AD Connect and some mapping (filtering?), but my Google-Foo has failed me and I can find next to nothing that would provide any guidance on this mapping. I'm not trying to solve any issue with Teams, just how to propagate on-prem data to a specific Azure field. Can anyone provide any guidance towards a/the solution? Help me Obi-wan Kenobi, you're my only hope! Jim

Answer 1

This should be updated based on the value of telephoneNumber in AD. To add an extension, use the following format: +13215551212x123 where 123 will become the extension.