Before departing for your tour, contact your cell phone provider to find out the rates you will be charged when visiting another country. Many providers have international phone and data plans.
Unless the proper arrangements are made, international phone use can be quite expensive, and you do not want to return home to an unexpected higher-than-anticipated bill. Great care should be used with regard to cellular data (email, web, etc.). Data usage on your cell phone can add up quickly and become very expensive.
Cell phones can also be rented from an assortment of companies offering a variety of overseas rental programs.