Sky subscription cards when initially activated are paired to the box they were activated in. Once activated they can be used to a more or less limited extent depending on your subscription in any other Sky box without the need for pairing to the other box. Pairing is definitely required to view Premium channels and full use of Sky+ functions. Playback of all but recordings from unencrypted channels is limited to recordings made with that card (or previously paired card when cards are swapped for a new issue). With unpaired cards you can view any channel you subscribe to except Premium channels (Sky Movies and Sky Sports). With unpaired cards you can view any recordings made with any card on unencrypted channels and providing the card has Sky+ active on it you can make new recordings from unencrypted channels. If the card was previously used in the box and has now been paired to a new box providing it still has a valid subscription for the channel concerned you can use it to view any recordings from non premium channels made when that card was in the box (to view previous recordings made with that card on premium channels then the card will need "re-pairing" with the box and then afterwards "re-pairing" to its new box. Sky unless a mistake has been made when card was issued will only change the regionalisation of subscription cards if you move to a different address within a different region - they will NOT normally do this on FreesatFromSky or cancelled subscription cards. With FreesatFromSky or expired subscription cards once activated pairing is not required and Sky will not normally do so. Current active white cards will allow viewing of the up to 10 FTV channels and regionalise the channels according to the postcode it was issued to. Old blue with yellow house cards will still regionalise the box and put Five on the EPG but will not allow viewing of the FTV channels (which will in some regions include ITV1 and Five). As an aside my old yellow house cards now replaced with new white cards which had Sky+ active on them will still allow playback of recordings made with any card on any box of non-encrypted channels. All activev cards FSFS or subscription require regular "keep alive" signals from the satellite so need connection to a dish and box being connected to the mains at very regular intervals otherwise the card will go to sleep and take some time (up to 72 hours) to fully wake up and on the latest white cards it has been reported that some require a phone call to Sky to re-activate.