Making International Calls

Dialing another country:
Dial [International Access Code/IDD] + [Country Code] + [city/area/trunk code] + local number
Dialing within a country:
Dial [NDD (National Direct Dial Code] + [city/area/trunk code] + local number

Calling from the US:
e.g. Calling Geneva from the US
e.g. ITU Geneva Voice:	+41 22 730 5111
US International Access Code: 011
    Switzerland Country Code: 41
            Geneva City Code: 22
Dial: 011 41 22 730 5989
 See Country Codes
 
 ISO Codes - An Internationl Dial Code Directory
 
Sometimes numbers will be listed with a leading 0 (The NDD - National Direct Dial code)
e.g. Visit Scotland Call 0845 859 1006
UK Country code: 44
Business Rate Numbers in the UK use 845 (which is not a city or area code)
Dial: 011 44 845 859 1006
Note some of these 845 numbers only work from within the UK


Calling out from another country:
  Each country has their own international access code
  It is 00 for most european countries
  See How to call international - International Dialing Codes
  
 

   
  Eg. to call the US (AT&T dir service) dial: 00 1 800 555 1212
  
  Some long distance carriers have their own local equivalent of an 800 number to 
  dial back home. See:
    Verizon Calling card - Dial Access Number then Service code (634)
         UK: 0-800-914-1346
    Iceland: 800-82-54
     Canada: 1-800-255-2255
    Verizon Calling Card instructions.
    
 AT&T
   Wireless International Rates - Wireless from AT&T
   Ireland $1.39/min
    
 T-Mobile
     Dial-a-Code provides access at local rates from the UK
      From a T-mobile phone dial 150
      From UK landline call 0845 412 5000
      Support: How do I use my US phone in Europe? | support.t-mobile.com
      
  Sprint  
  IntlCoverage | InternationalRoaming.sprint.com
  
  
See Telephone Number Format
 and Telephone Information for links to country, city code lists and international access codes.
 
This used to work from all phones with the old AT&T system.
You may now have subscribe to an international plan to call internationally.
With Optimum/Cablevision it was a $10 sign-up fee for call-by-call billing
or $19/month for 250 minutes per month.

Using a phone in Europe

• Call your service provider to provide roaming in Europe.
  It was free with my T-mobile account.
  Calls are about $1.29/min and texts 35¢-50¢
• Subscribe to an International Service plan if you travel a lot.
• Get your phone unlocked (T-mobile will send you a code to do this)
  and rent a SIM card to work with one of the local carriers.
  (Note it may take a week or more to get this code.)
  

• Advantages: You do not pay for incoming calls, so your friends in the US can call you in Europe using an inexpensive calling plan (they pay the costs for the long distance call - you pay nothing). Outgoing calls within the country you have the SIM card for are relatively inexpensive.
• Disadvantages: You have to buy an GSM cell phone and a SIM card. People calling you from the US have to dial a European number. If you do not travel to Europe every year, your phone number (on the SIM card) may expire.

Dialing:
Within the country [NDD (National Direct Dial Code] + [city/area/trunk code] + local number
e.g. Scottish Tourist Board
0 845 859 1006

Outside:
e.g. UK to AT&T dir assistance
00 1 800 555-1212

Using a phone on a cruise ship

Glossary
CDMA Code Division Multiple Access - Communication standard used by Verizon and Sprint
CSIM CDMA2000 Subscriber Identity Module 
GSM Global System for Mobile Communications - Comm standard used by AT&T, T-mobile
      and most European carriers. 
IDD International Direct Dialing Code - Access Code to dial an international call
IMEI International Mobile Equipment Identity (Dial *#06# to get to display)
MEID Mobile Equipment IDÑa superset of IMEI
NDD - National Direct dial Code
SIM - Subscriber Identity Module UICC card for CDMA phones 
UICC Universal Integrated Circuit Cards (SIM card for GSM)

See also: TeleBright Glossary

Links:
Country Codes
How to call international - International Dialing Codes
International Dialing Codes | bspage
PrePaidGSM.net
Rick Steves' Europe: Public Phones, Hotel-Room Phones & Phone Cards
Mobile phone technologies
Using Your Cell Phone in Europe | Budget Travel
What Is the Difference Between GSM and CDMA? - wiseGEEK