In our infra,we have 2013 pool and 2010 pool running side by side.All users are migrated on 2013 servers.
For some users address book is not coming at all.If i move users back to 2010 it will download address book or if i install lync 2013 client in machine it will work.
Only not working if user id is on 2013 lync servers and machine client is 2010.Please suggest to solve issue.