Do you pay the BT line rental through Orange/EE or still direct to BT? I ask because I am currently on the deal from BT where I paid my line rental up front for a year (£5/month saving IIRC) and that runs until the end of the year.
I had my landline telephone with BT and paid for the line rental 12 months in advance on line rental saver, you will have to wait until the end of your contract then move, otherwise it will cost you.
Unless you claim your contract buyout credit from EE after you join their broadband and telephone services.
EE/Orange also have line rental saverů
Line rental Saver
Line rental is £14.75 a month, or you can choose Line Rental Saver.
Line Rental Saver allows you to pay for 12 months line rental in advance by debit or credit card with a non-refundable payment of £132, the equivalent of £11 a month. It cannot be paid in instalments. Each month you will receive a monthly line rental credit on your account.