Travel Technology - help me with my month long Paris makeover

I will need two GSM phones. I have an AT&T iPad already (gen 1).

I would like a good VoIP adapter I can plug into a router, with service that lets me plug in a Panasonic cordless phone and make and receive calls as if I am in the USA. I'll be staying at an apartment with supposedly fast cable modem service.

And I would like to be able to do voice / data in France when I'm there.

What would you suggest? I prefer going with quality VoIP services rather than free ones like Google Voice given a choice...

Thanks

I have been using MagicJack for over 4 yrs unlimited calling to US Canada from any internet connection with enough bandwidth.

You can plug it into a connected computer via USB and use talk headset via the audio in/out
OR
RJ45 the jack directly into a router and plug in a phone via RJ11 and the power adapter to a n electrical outlet.

So, if you have a wired internet connection (or a router that accepts a wireless card such as Cradlepoint), I believe that either an Ooma or Vonage box can be plugged in. I've not tried it, but unless they block foreign IP addresses it should work.

As for cellphones, almost any unlocked GSM-type devices should work. Either get a local SIM card or spring for a cheap roaming-type prepaid SIM.