In our environment we use Microsoft Lync 2010. I've noticed that none of the user profiles in sharepoint have their sip address field populated. I checked the Sync service and it appears it is trying to get sip addresses from the
"proxyaddress" attribute in AD. The sip address does appear as the 1st entry there, however a better attribute to use in an Lync enabled environment is msRTCSIP-PrimaryUserAddress. I tried to re-target the import to that attribute and it
appears that Sharepoint 2010 doesn't offer that as a selectable attribute to import from. Is this by design, a bug or something broken in our environment?