Can you facetime another iphone 5S abroad without Wi-Fi?

I live in England. My friend lives in California. We both have an iPhone 5S, can we FaceTime each other for free without using Wi-Fi?
Does one of us have to be connected? Or both? My Wi-Fi is not working in my house. Any help would be greatly appreciated and I will give a best answer!

If both of you use any sort of internet you will not be charged unless you go over your monthly data allowance. To reduce Data usage when facetiming, switch video off.

You both need to on the "net" Wi-Fi or 3g/4g for this to work, cheers.

Yes. Imessage and Facetime are both free even internationally.

Don't think so

You'll both need an internet connection whether it be Wi-Fi or cellular. I wouldn't do FaceTime without Wi-Fi unless you have unlimited data

You can use FaceTime without wi-fi if you enable cellular data for FaceTime, but it won't be free. FaceTime uses about 3 MB of data per minute, depending on the specifics of the connection. Slow cellular connections might have trouble keeping up with FaceTime but more recent protocols like 4G/LTE have no trouble if reception is okay.