We cancelled our BT line rental last year and, as I recall it (though I didn't make a note at the time), were told that there would only be a reconnection fee if the line were physically removed, requiring reinstatement.
This is only if you go to a cable provider such as Virgin media and elect for them to replace your existing cabling with theirs - not something they would typically do as they dont like to touch stuff that might break something else.
Most of the other companies work on a re-lease of existing bt infrastructure - referred to as unbundeling they can undercut the bt margin cause bt has had restrictions put on it for "anti-competitive" purposes.
call100:
Of course you could ditch the line rental completely and use VOIP. I have been using it for two years now and its never let me down. With free calls to virtually everywhere in the world (which I take great advantage of) as well as the UK. Plus all the usual phone add ons....Voice mail, 1471, call waiting, 999 capability...etc etc etc. All for £7.50 pm No line rental. If you want it cheaper than that you can get it with a few less extras from various companies....
I'll never go back to BT
Your paying either bt line rental, paying for ntl line rental (and on top of both for interenet service) OR your paying for a wireless broadband connection - either way your paying for for VOIP connection over and above the cost of the calls.
What about people who are trying to call you and don't know your mobile number
VOIP in this respect is data over a mobile network so has nothing to do with a mobile number.
Now for the reality.........
Voice over IP I have a very good knowledge of because I work with it day in and day out on a carrier level (i.e. not residential subscribers but telecoms companies to telecoms companies). The big disadvantage which is being addressed in legislation because people are wanting to move to this cheap medium is there is no provision for emergency access. I VoIP number connection can be dialled from your machine regardless of where that machine is - this differs from a traditional tdm telephone line whereby you know point A is connected to point B.
Add into this the requirement for your standard tdm phone line to provide a 50v feed to power a phone regardless of if your electric has been terminated for possible emergency reasons and you see the inherent problems with VoIP in a residential environment. To accomplish this in a VoIP environment you need your internet providing mechanism (Modem, DSL Router, etc) to be up and running as well as providing power to the handset.
VoIP is in its infancy