I just buy an unlocked cell phone and buy a sim card for each country I go to. When I go to France, costs me 20 Euros for unlimited calls (including to the US), unlimited texts and 3Gb of data.
What if someone wants to call me? If I'm abroad it's mostly for vacation, I can give my new number to family members wishing to contact me. If I can't do that? I still get texts and voicemails through Google Voice on my phone. And if needed I can enable calls through data on my phone using hangouts.