Porting out landline number while still on FTTC contract

[slarty*1]

I am on a FTTC contract with a landline (but no boost extras).  I am considering porting out the landline number to a VOIP provider (to give added flexibility).  What happens to my current TalkTalk landline/broadband package if I do that ?  Am I just assigned another random landline number to the line  (which I would probably never use?).  And would I be charged (by TalkTalk) for making the port out request ?

[Gliwmaeden2]

Your current landline number is integrated with your Broadband Service, so can't be separated at this stage, @slarty*1. It identifies your account. 

AI:

Service termination: Porting your number to a VoIP provider will automatically cancel the original landline and FTTC service that is connected to it.