If you are issued with a hub 3 [or take up Infinity] your BBTalk number will be withdrawn.
That said, BBTalk does work with hub 3 on BT Softphone; Android app with Sipdroid [VOIP]. I havent tested hub 4 yet. If you still have your number you can poosrt it to a third party VOIP provider at the moment.............
You can request your BBTalk be kept and it might be until the serviice is withdrawn for all of us - exactly when that will be changes from time to time.
Someone else might be able to add more. If not, best advice is watch this space.
AQ. "Welcome to Royston Vasey - You'll never leave."
The phone itself is actually a normal DECT phone, and is connected to the hub like any other digital handset, and will work on your normal landline number, when the extra Broadband Talk number is ceased.
You can prove this by picking up the handset and dialling "5". This will result in the phone connecting to your landline number, and you will hear the dial-tone change to normal.
This means you can still carry on using the phone handset.