For an iPhone to just get phone calls and texts you should need to go to Settings > General > you then have options for Mobile data on or off... This will only use data if your connected to Wifi.... If you have it on already you can turn off Data Roaming aswel. Thats from my iPhone 3GS, knowing Apple its the same for the 5...
For the next 60 seconds, I will conduct a test of my emergency broadcast equipment. AAAAHHHHH!!! Had this been a real emergency, the scream you just heard would be followed by lots more just like it. This concludes My test of my emergency broadcast equipment.