We have been asked to provide a One-time-password solution to our company. This obviously is a problem for mobile devices that synchronize with Exchange, in that every time the password change, the users have to manually change the password on their device. I know that Microsoft provides certificate based authentication with their activesync protocol, but the problem is that it is only supported on Windows mobile (not all versions). We have to support Windows mobile and Nokia E-Series (S60). I know that the SA2000 supports mobile devices, so my question is whether anyone have done this kind of thing with SSL VPN, or can anyone point me in a direction because I am pretty much at my wits end.