Broadband upgrade

can anyone throw some light on this for me - I use dial up 56k and
can now upgrade to 512k broadband at no extra cost. I know that this
will increase the voltage to my telephone line (approx 50v to 100v)
what I am not sure of is wether I will react to this change.
especially the telephone point in my bedroom. I currently only plug
the tel wire in when I need to use the net and then unplug it (tel
point in my bedroom). When broadband is initiated does this change
the characteristics of the tel line permanently (higher
frequencies/voltage etc)or only on demand, ie. I would do the same
plugging/unplugging regime with broadband kit.

Of course the positive side can be that you can work faster and thus
get off pc quicker ?! plus not miss any tel calls.

Since broadband comes as a 12 month contract I cannot afford to make
a mistake here.

Can anyone shine a light here for me ?

kind regards

Paul - ps I am a new member, but have subscribed to ESUK since it
began - THEY URGENTLY NEED FUNDS BY THE WAY.