sorry, think i was getting a bit out of touch with your original request.
At present the phone line to your new house has a number assigned, but this number isn't assigned to you. So if someone made a call, BT wouldn't know who to bill. The line is therefore barred via software and is ready to be activated. You can activate it but I expect a 12 month contract to be the way it would happen.
The TalkTalk new line stuff doesn't really say whether it includes activation of your existing line, but since yours is a common situation I assume it does. Looks like its a £50 charge.
Andrew says the cash-back stuff doesn't really work in this situation, so I think take that as gospel.
Looks like you need to call TT and tell them the situation, or you could try the number you are getting from 17070 in the cash-back site.
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