Calling another US cell phone in Europe

A mobile phone always keeps its country code and area code, no matter where it is. It remains, telephonically speaking, in a bubble of the country it belongs in.

The safest way is to always add the country code and area code. You will not be charged extra if you put these codes in when not needed, but you will then be sure you will always get the correct number no matter where you are. I always save numbers on my phone with the full country code.

On a GSM phone, you can put in '+' as the access for an international call, that way you don't need to worry about tthe countries which have different international access codes:
For example, a number in London: + 44 20 yyyy yyyy (without the spaces).
A number in Switzerland: + 41 aa yyy yy yy
A number in the USA: + 1 aaa yyy yyyy

Yes, you should be able to dial like normal to call your wife in Europe. When I call home from Europe with my cell phone, I don't have to change anything - I can simply call people in my contacts. Nothing to change or add.

ditto the other responses, I've done this many times while traveling in Europe and Asia. In the olden days, you would press the "*" key to access the "+" symbol, but with smart phones the "+" symbol can also be the same key as the "0" key or another key.

You can also dial 001 555-555-5555, substituting "001" for "+1". I used the plus with my old flip phone on previous trips, but in October I brought my iPhone to Europe and dialed with 001. Much easier.

Depends on your calling plan. Get specific introductions from your service provider as to how to use the plan you buy in England and France.

We live dangerously and travel without a phone that operates internationally. During our last year's trip to China, another couple in our tour group purchased some kind of short term plan that enabled their cell phones in China for a short (month?) duration. ( It may have been an AT&T plan). It took them 2/3rds of the trip to figure out how to use their cell phones in China only succeeding with help from our guide talking to China Mobile. The bottom line was their short term international plan enabled their phone to make calls as if they were in the US -- No country code prefix, just the US area code and number. Using the China access code while in China for calls to a US phone resulted in a failure to communicate.

AT&T "Passport package" on calling home (another US phone?):
https://www.att.com/shopcms/media/att/2015/shop/wireless/documents/Travel-Tips.pdf

How to call home • To call or send a message back to the U.S., dial:

+ (1) (10-digit number). The “+” sign typically appears if you press and hold the “0” key on your dial pad. • To call or send a message to
another country, dial: + (country code) (local phone number).

The OP is asking about calling each other while they are BOTH in Europe, not calling home to the US or calling someone in Europe. Chris has the right answer.

Chris provided the information you need. Simply add "+1" to the regular 10 digit phone number and then call as normal. You might enter that number combination into your directory as the default number, to allow "one touch dialing".

If you call your wife, you will pay for the outgoing call and she will pay for the incoming call (or vice versa) on each call, according to the terms of your roaming plan. Texting will be a much easier and cheaper option.

First let's assume you have the wife's name / number in your contact list. If that is the case you might be able to just highlight her name /number and hit send. The call will probably be bounced from where you are back to the states and then back to her -- at least that's what I've been told by the international dept. of our carrier. Best to check with your carrier's international dept. since things may not operate on your carrier's system as ours does.

Nancy: "The OP is asking about calling each other while they are BOTH in Europe, not calling home to the US or calling someone in Europe."

I highly doubt it will matter if both are using US phones in Europe. If one or the other had a local SIM card, it would be a different story.

Consider this: do you think people in the US calling a US cell phone which is in Europe need to add digits/pluses to the regular US phone number for it go through? Of course not - they just dial the US number without knowing where the person they are calling is. Same with someone also in Europe with a US phone calling another US phone.

Andrew H,

"Consider this: do you think people in the US calling a US cell phone which is in Europe need to add digits/pluses to the regular US phone number for it go through? Of course not - they just dial the US number without knowing where the person they are calling is. Same with someone also in Europe with a US phone calling another US phone."

When calling a U.S. number from Europe (even with a U.S. phone), using the "+1" prefix IS necessary. The "+" symbol is a substitute for the "011" prefix and the "1" signifies a long distance call. When a call is placed in Europe from a cell phone with a U.S. number TO another cell phone with a U.S. number, the call will first be directed back to the U.S. and the network will then locate the number being called and transfer the call back to Europe. The calling party will pay for a long distance call to the U.S. in accordance with the terms of their roaming agreement, and the receiving party will pay for an incoming call, again in accordance with the terms of their roaming agreement.

People in the U.S. don't have to use the "+1" as they're simply calling a local number and not making an international long distance call. Of course, if someone in New York calls a number in California, they will have to use the "1" and will be making a long distance call. In any case, the network will find the phone if it's registered on any foreign networks (registration takes place when the phone is switched on after the flight), and the person receiving the call will again pay for an incoming call in accordance with the terms of their roaming agreement.