Assumptions and questions from a complete dummy
 

I've never traveled abroad with a cell phone.
I bought 2 Samsungs with Tru SIMs off ebay for an upcoming trip to Europe.
I know nothing about international dialing except you must use a country code when calling. I assume I need to put in country codes in when loading my contact for calling back home.
I plan to activate the SIMs with local (Missouri USA) numbers. I won't be making many calls so price per minute is not terribly important.

When I'm calling my wife at her USA number even tho she's close by but we're both in another country do I dial the USA country code?

If I make a local call while abroad do I dial the country code even if its just down the street?

Be gentle, thanks

Country codes.
 

Yes. Yes. You know me. As you know I am also using Tru. You will have US number. You will be calling US numbers in the US and elsewhere. I just tested calling a US cell phone [not Tru]. xxx-yyy-zzzz, 1xxx-yyy-zzzz, and +1xxx-yyy-zzzz all work. I would suggest when you program your contacts for the Tru SIM you use the +1xxx-yyy-zzzz format. This should work whether you are in the US or not. And does not need to be reprogrammed once you do it.

Country code: in the US '1' is the country code [also Canada].

In the UK '44' is the country code.
The US use of 1 before US long distance calls is not used to my knowledge anywhere else.

Outbound international call codes. threre are many. You probably do not even know what it is for the US to dial an international number from a land line phone. I don't off the top of my head. The good news is you do not need to know. The '+' at the start of the number is the international 'code' for outbound calls recognied by any GSM system to tell them to use their countries code followed by the number.

Wherever you are outside the US [and I encourage you to use it in the US] you will dial +cc wwwwwpppppp [arbitrary letters to indicate phone numbers.

The next sentence I believe is true and I expect people in Europe to clarify it for us. This is a kind of exception. Many phone numbers in Europe, for instance when calling in country have a number like this: 0wwwwwppppp. With a leading 0. Let us say the number is for the UK. To call it with a non-UK phone you would dial +44wwwwwppppp . You drop the zero to make the call.

If you metion what countries you will be going to we can give you the country codes for them.

Wikipedia to the rescue!
 

Country codes you dial to:

List of country calling codes

What the '+' is really. Why '+' is a good thing.

List of international call prefixes

Study this and know more than most americans.

With GSM you can always dial like it's international even if it's not and the call will complete and will be charged as a local call.

Your message is a little confusing. You say you are "going abroad" does this mean that you are going outside of the US or you are flying to the US and that is your abroad? In any case you can make a local call either the way the locals make it or using +country code/area code/number. It will cost the same either way. To call a number in the US for example 311-555-2368 you'd key +13115552368. If you were calling a number in London, England 020-7654 3210 you'd key +442076543210. Most phones you make the + character by pressing and holding the 0 key. Nokia phones you press the * key twice quickly.

We plan to go to Europe from the US.

I guess the only unanswered question is this one.

"When I'm calling my wife at her USA number even tho she's close by but we're both in another country do I dial the USA country code?"

Yes, and......
 

Yes, but not only the country code, the '+' also. That is why I suggest you preprogram your phones with the +1xxxyyyzzzz format and test even before you leave Missouri.

Thanks...........