I have looked through the dbus interface of Kopete (KDE4).

When I call the method "contacts" or "contactsByFilter", I get a list of all contact ids. Almost all of them look like "::".

When I copy & paste this contact id to another method (e.g. getDisplayName or sendMessage) everything works fine.

Now the problem comes: Some contacts have a contact id that looks more like this "wMIG8yUoVm". I've found out that those are the contacts which I conntected to the adress book.
Those ids are really bugging. All other dbus methods can't do anything with does ids. ("displayName" returns an empty string; "sendMessage" or "openChat" do nothing)