To call your friends worldwide it's easy, you just need to use the international format:
+ (country code) (area code - number)
Here are some examples :
To call your friend in France, dial : +33 ( erase initial 0 from area code - number)
To call your friend in Mexico, dial : +52 (area code - number)
or +52 1 (area code - number) if you want to reach a cell phone with a 2 digits area code,
To call your friend in Philippines, dial : +63 (area code - number)
To call your friend in Pakistan, dial : +92 (area code- number)
To call your friend in Chile, dial : +56 (area code- number)
To call your friend in UK, dial : +44 (area code- number)
etc...
A quick search on any browser will yield the country code of any country!
Don't forget the "+" , do not dial 00
(tap a long 0 to dial +)
Otherwise, you can also exclude the country code from the number you are dialing, but tap on the flag (in the dialing screen) and choose that of the country you are trying to reach!