Not really. You can place an international call from your cell phone in the same way you would dial from a landline: International prefix - Country code - National subscriber number. In addition, when dialing abroad from a cell phone you may replace the international prefix with the plus (+) sign. You can dial + by long pressing zero on many smartphones.
Generally, when using your wireless plan to dial internationally, rates can be much higher than what you would pay using a VoIP service for example, or a calling card. As an example you could pay less than 10 cents a minute using a calling card while your cell carrier would likely charge you 30 cents/min for the same call. Of course, things change rapidly and often for the better in the telecom industry due to both technological innovation and increased competition, so the best advice we can give you is to check with your wireless provider for their current international rates and plans.