Digicipher II recievers have a unit id number stored in them in a memory chip that's powered by a special lithium battery that should last a fairly long time (like 10 years or more). This unit Id number is unique to each receiver and used to authorise the reciever by the programming providers. That is whenever you purchase programming you'll have to give them this number and they will send an authorisation hit to your reciever using this number. There's no way you can change this number and if the receiver ever loses the number for any reason, like maybe the battery goes dead, your receiver is effectively dead and will never be able to receive DCII programming again. Anyway, certain models of recievers may have unit ID numbers from different ranges of numbers. This is the case with starchoice DSR-405s and it's american cousin the 905. Therefore if you attempt to subscribe to 4dtv programming with a 405 or any other starchoice reciever at the moment you give them the unit ID number they'll immediately recognise that it's a starchoice receiver and they will not authorise it for you. They're not allowed to by the DCII gods (general instruments and motorola) who have complete control over DCII. The same thing is true if you have a commercial DCII receiver. That is if you attempt to subscribe with a commercial DCII receiever they'll know by the unit ID it's not a 4dtv unit and won't allow it. So, if you want to subscribe you gotta use the right receiver (in this case either a 905,920, or 922).
As for the HD decoder, the good news there is it doesn't matter as the HD decoder only decodes video and has nothing to do with the decryption engine. So, you can use either an HDD-200, HDD-201, or even an HDD-1000 (if you can find one).
