You should be able to dial a fully-qualified number from either side to anywhere, including that side. I store any number which I may have to dial internationally as a fully-qualified number, with a leading +, a country code, and the local number.

Dutch or French Side to US +1-212-555-1212. The "+" is usually generated by holding down the "0" key.

French Side to Dutch Side +1-721-nnn-nnnn

Dutch Side to French Side +590-590-nnnnnn for landlines and +590-690-nnnnnn for mobiles.

While I'm not shy about using my US mobile if I have to, I've owned a personal French-side pre-paid mobile for years. I use that for most of my calls, and in conjunction with a calling card for international calls.