MultiUser Phone - Logon-Logoff

Hi,

I trying to implement a multiuser phone, so the user can login and logout from the phone. This is easy, I use "devicenduser" features and I acomplish this multiuser phone using "*11".
But Now I need to make the same but with a large number like a "pin number".

EX: Card with number: 1234593828349232 (used for authentication)
Number to call: 61234567
The phone es NOT associated to any user!

So the use should dial the following in his phone: 123459382834923261234567
So I can detect the user whos is making the call and can associate the phone to the user.
After dial, the phome must be deassociated form the user.

Any ideas how to do this?

Thanks,