How does the call forward work internationally?

So say I was traveling abroad. If I turned my iPhone to call forwarding to my google voice number then received my calls from my cell phone on my google voice number. Will it charge me international rates because the phone is overseas? Will it even forward if my phone is not receiving cell signal?

Call forwarding happens at the phone switch. If you set call forwarding and then turn your phone off, it should work fine, no extra cost.

A famous problem to watch out for is voice mail when travelling internationally. In many cases, you'll pay for an international call when a call is routed to your phone overseas, and a *second* international call when the call goes back to voicemail. The solution is to turn the phone off, or at least turn off voicemail while you're travelling.