In many countries the Calling Party Pays principle is applied to mobile phone calls. What this means in a few words is that the caller always pays for the call, including the termination charge, while the callee does not pay anything to receive calls on their mobile phone. It's the reason why, in many countries, charges for calling a cell phone versus a landline are different, generally higher when dialing to a cell phone.
Considering the above, make sure you know what type of number you are calling when dialing overseas. Moreover, make sure you are fully aware of the rates charged by your phone service provider for calls to landlines vs mobile phones in the country you are about to call. Often telephone companies more prominently advertise rates for calls to landlines because they are much lower.
Cell phone numbers in most countries outside North America do not use area codes. Instead they use unique prefixes assigned to all mobile numbers regardless of geographic location. This website provides dialing code information meant to help you differentiate between fixed and mobile telephone numbers in most countries.