Check if your area has 4G/LTE coverage. This will be more suited to handle bursts of data that can be processed by your central Server application. If not then a modem can be attached to your PI-3. The issue is the impact using VHF with other RF frequencies. Interference with other bands is a legal issue.
It is better to look at the PI-3 Community and check if an existing project can be re-used.
If your project is based in IOT – Internet of Things – using M2M then I will be glad to help.
VBR/ Wallis Dudhnath