I changed my old nokia a couple of days ago to a 6120 classic. The old phone worked perfecly with the bluetooth on the F-series, transfering contacts was very easy and with no problems... My new 6120 runs nokia's S60 3rd edition plataform witch is the same plataform that other more sofisticated nokias like the N-series run. At first connecting both devices was easy, like everything with nokias, but when I was about to transfer my newly organized contacts to the head unit, it didn't transfer anything. I started to see the options on the phone and was able to transfer one contact, but I wasn't going to do that 160 times..... So did a little research and found a solution for any of you nokia users that are having this same issue.
1. You need to have Nokia PC Suite installed on your PC to connect it with your phone.
2. Go to this page: http://europe.nokia.com/A4143881 and download the Nokia 810 Contact Download Application. Make sure you choose the one that corresponds with the plataform of your phone. Mine is for Nokia S60 3rd edition devices so I don't know if the others will work.
3. Install the application on your phone with the Nokia PC Suite and then find it on your phone in the application menu or the inbox. Mine installed in Applications/Personal and the app is called Download.
4. Go to your car and pair up the F-Series with your nokia. Turn on the new application on your phone and then go to the phone menu on the head unit and start transfering contacts with the "Transfer Contacts" icon. That's it, it will take aobut a minute for all of the contacts to transfer. If that doesn't work, try it again, this time turning on the Download app at the phone before you pair it up with the F-series.
Hope this helps.