you can ring more than 6, you just have to create a ucd group, which will also illuminate all the dss lights for extensions so be aware of that..if you're just adding 2 more xt's to ring just go into programming and edit each co line 2nd section in the programming and add the xt's starting with co # 740.
voicemail you need to A. hook up with a serial connection and keylink or you can teleparamater in and create, given that the password is default for the supervisor mailbox or the customer knows it.