I saw in this other project that they use the SigFox network. This kind of network might be useful to your project. It looks like it is a french radio network, not sure if it exists in other countries.
I had the chance to meet Sigfox at MWC 2016 in Barcelona , and established a few contacts . The only issue is that their terms are not very friendly, asking a lot of money from day 1, including the test period. So I had decided not to follow this direction anymore, going instead for the more approachable LoRaWAN technology.
uRADMonitor A3 is the first unit that will feature a LoRA modem, allowing for Low Power energy transmissions.