The least expensive and convenient way to call the UK from USA.
Call a local number (speed dial on Cell or Home phone)
and then UK land line number. 01144 etc.   

It's called a Calling Card but there is no physical card.
Just a local access number.

Pay 1.4 cents per minute. One minute rounding.
No access, maintenance charges or connection fees.
No pin # (after first use)

I have been using the same card for years and they now have a
friend referral program that you can also take advantage of.

I get $10 for every referred friend that makes a first purchase greater than $10.
You get 20% Extra Balance on your first purchase. It's a win, win!

Please send an email requesting a referral.

Other great rates...  (as Nov. 2010)

Australia   2.3 cents per min.
Canada     1.5
China        2.0
Czech R    2.9
France      2.0
Germany  1.7
Hungary   2.5
Mexico     2.0 - 4.0
Poland     2.0
Russia      5.0
-Moscow  1.2
S. Korea   3.3
Taiwan     2.0
Thailand   2.5
Turkey      4.3
UK Cell     14.3
USA           1.7