Similar post in the Orange thread but worthy of mentioning here given BT's incompetence

Signed up monday having provided them with my Orange MAC code

four days later order has been accepted and cancelled three times and have endured endless call frustrations via BT Sales, Broadband Help and Order Management all of whom provided conflicting info as to the order status and the MAC code

BT suggest MAC code invalid, Orange insist it is valid, end result for me is deadlock - unable to move to BT and unable to get Internet connection back up and running with Orange

One possible scenario is that Orange have given you an LLU MAC and that BTs system doesn't recognise it as valid. Valid MACs follow the format LAEM1234567/1F6HT (if the first two letters are LL then it's definitely LLU MAC)

Orangeproblems.co.uk have a list which gives details of providers who accept Orange MACs along with a contact number, maybe worthwhile contacting BT on that number if you know the MAC is valid.

thanks for the above

Orange have confirmed it is an LLU MAC

Changing ISP's appears to be the telephonic equivalent of climbing Everest

Unfortunately when Ofcom revamped the migration procedures last year, LLU migrations, whether from shared or full, were not factored in. Hopefully the new guidelines, soon to be published, will clarify things. You may have to persevere with BT to find someone who knows what you're on about but they are "supposed" to be able to accept LLU MACs.