i added their names under "contacts" on google voice web site, but whenever those people leave me voicemails, google voice on the phone will tell me that i got a message from an unknown caller.
is it possible to change that?
i think that the only way is to turn on the "call screening", and let them to say their names first.
any other ways?
Look in your Obi Call History and/or GV Call History. If the calls have a phone number listed -- this will be the same on both histories -- they you can same the call as a contact and type in a name. Follow the advice in the other thread where you asked a similar question (http://www.obitalk.com/forum/index.php?topic=4707.msg30681#msg30681).
If the calls show as unknown number or whatever, then there's no way for GV to associate a name to any of them.