I think you can do it without a phone: The French people are great at helping. Just start out saying that you're sorry you don't speak French, and that you need help. Something like: Pardon-- Je ne parle pas francais-- je suis desolee, mais parlez-vous anglais? J'ai besoin d'aide.
I depended on tourist offices or the marie (village office) to help. They speak english at the tourist offices. I would take some index cards with some french phrases on them, so you can hand them to people when you need help.
I joined up with a group at Le Puy for a while and a french speaking woman took the reponsibility of calling ahead. But then I split off by myself, and just showed up at a gite and that worked fine. I walked Sept/Oct 2017. I don't think you're going to find full gites, it's more likely they won't be open or have made food. Though-- that never happened to me. There was always plenty when I just turned up.
When I went on the alternative route to Bonneval, I was alone during that whole walk. At the turn off from the main chemin, I asked someone walking (college age person--I figured he could understand english a bit), to call ahead to the village Condom d'Aubrac for that night and to the Abbeye at Bonneval and tell them I was coming. At Condom d'Aubrac, the village office stayed open for me, and the woman there gave me the key to the community center (gym mat on floor in small heated room, kitchen. No-showers, but hot water, and radiators where my washed socks dried overnight). Upon finding that I had no food, she went and got the cafe owners to open the cafe and make me dinner, then breakfast the next morning, and they packed a nice lunch for me too. -- (The community center was a donative, and I paid for the meals at the cafe.)