Not really. You can place an international call from your cell phone in the same way you dial from a landline: Exit Code - Country Code - National Subscriber Number. In addition, when dialing abroad from a cell phone you may replace the exit code with the plus (+) sign. You can dial + by pressing the * button twice on some phones. Others may achieve this in a different way.
In most cases it costs much more than you would pay using a landline or even better a calling card or VoIP service. As an example you could pay less than 10 cents a minute using a calling card while your cell carrier would charge close to $1 per minute 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 current phone service provider for their current international calling plans/rates.