We used BlaBlaCar successfully along the Camino when we needed rest days but still wanted to progress forward. I downloaded the BlaBlaCar app. When it came to the phone number, we used the USA cell number of one of our party, who had the cell service necessary to receive the confirmation code (I only had wifi, no cell service in Spain). I included a picture and other information (ie pilgrim from USA, age, etc) in my profile. We generally found BLaBlaCar to be convenient and inexpensive. I definitely recommend! and you do need to have a valid phone number that has cell service.