I subscribe to the 'Unlimited FreeServe' package which basically means that I get a monthly charge of £10, and in return get free Internet calls at any time of the day or night - genuine 24/7.
To connect to FreeServe I use BT HomeHighway (which gives me two analogue plus one digital line in/out of the house), coupled to the digital line is a BT-Ignition ISDN Terminal Adaptor (aka. a digital modem).
For using the HomeHighway system I also pay BT £39.99/month - this includes £13 of 'free' calls.
Nb. One of my analogue phone lines (the one that gets the most use) has a little FreeServe gismo attached to it that automatically preceeds any numbers I call with the code to direct my call via the FreeServe network.
As you might understand, being a PPRuNe administrator, I have the need to use the internet a lot - and so fast/reliable access is a bonus; Thus all in all I'm quite happy with my setup. Connection rates are always 115,200 baud, and the typical time to connect is about 3 seconds (during the afternoon when all the kids get on after school it can take upto 30 seconds).
Ps. Don't be fooled by the daft connection rates that some ISP's claim. They may indeed be able to connect your computer to their system at that, but you should always remember that, in general, the speed of down/up-load that you will percieve is going to equal to the slowest server/router in the link between you and the site you are accessing !