Cheap way to phone a cell phone in the united kindgom from the states?

I met a guy when I was in london and phoning each other has become extremely expensive. Is there a way to make a call to a united kingdom cell phone for cheap? Everything i see is only for land line phones. Suggestions greatly appreciated!

T-Mobile has an international monthly payment which for a small monthly payment allows you to call cell to cell for approx 20 cents/minute.

You can always install go2call.com on your PC and then using a headset(can be done without if your PCs mic and speakers are good enough) you can call the UK for 3 cents per minute

IP phone sevice through you PC cheapest way I know of for international calls