Hmm not sure if the Americans are reading this post but I have Vonage and I do know it is also available in the UK (looked into should I make the move there)... on the US end you pay about $25 a month, it hooks into your high speed internet but you can use a regular standard phone (and you get all the standard features, call waiting, voicemail etc included) and for that standard fee every month (you can budget yay!) you can call within the entire US and select countries UK being one included for free - so all of your calls to your significant other in the UK doesn't cost anything and is covered in that one monthly fee and I also believe you can transfer your current phone number (I think it only charges a low, as in a few cents, if you call a UK mobile phone, landlines free)... I believe the UK to America fee is about 5 or 6p a minute all the time... something to maybe look into, just google vonage or vonage uk
Cheers!
Angela