I'd follow the BE scheme, but would add a slash in order to separate the area code from the telephone number: +49 (0) 89 / 487 33 76

1. The + sign is common.
2. There is no correct or incorrect way of grouping, save for a company prefix; in this case, I recommend "2345-6789" (2345 = company prefix).
3. Brackets: as shown above

Sorry, habe Dich komplett missverstanden.

I'm looking at a business card of a German attorney:

+49-(0)89-28627-202 or 0 (meaning extension 202 or the switchboard)

@ Verfasser et al: Are you trying to find customers for the respective person ?!? . . .

Honestly! - Never learned to camouflage an actual number ?? . . .

@ # 4, Hi daddy, the number in # 3 is purely fiction :-))

... have you tried it out at our business-hours ?! - I bet, somebody will answer! . . . ;-))

The traditional US practice was to put the entire area/city code in parentheses, and to group the local number with hyphens in groups of 3 or 4 digits (not 2):

+49 (089) 555-1234

However, the parentheses are often no longer recommended now that many larger US cities have several area codes within the same city and therefore mandatory 10-digit dialing even for local calls. And if you use parentheses for the whole area code, you can't use them for that pesky leading zero in European area codes, which has to be dropped in international calls.

To me, the main thing is that it's helpful to show where the city code ends and the local number begins. Data's slash after the area code seems like a good idea, and I've seen that used in some travel books:

+49 (0)89 / 5555-1234
+49 (0)821 / 55-1234
+49 (0)171 / 555-1234
+49 (0)3691 / 5-1234

If you don't like the hyphen, you can divide the digits in other ways, with spaces, periods, whatever. I personally find groups of only two digits somewhat harder to read, but that's probably just because it's not a US convention at all.

An office extension, if you have to wait and dial it after you hear the voice-mail prompt, should be preceded by a clue such as 'x' or 'ext.':

+49 (0)89 / 555-1234 x77
+49 (0)89 / 555-1234 ext. 77

Helmi and hm-us: Thank you very much. This is just the kind of information I was hoping for.

Now can anybody help with the UK version?

After reading what all the others wrote I have to say that I do not agree with everything.

1. + marks that the following set of numbers as the country code.
2. The ideal grouping allows for separation of country code, area code (=Vorwahl), number and extension
3. you can use brackets for the area code

Since in Germany you never dial the leading 0 if you dial with country code I suggest - and have seen this on many business cards - to leave out the leading 0.
A number +49 (0)89 123456-78 can be confusing when called from abroad.
A number +49 (89) 123456-78 is much clearer. And people inside Germany know to add the leading 0 to the Vorwahl.
There are other countries where a leading 0 in the area code is to be dialed even when dialing from abroad, e.g. Italy.

Good point. I guess it depends partly on whether you think people will use the business cards more from outside the country, in which case AGB's suggestion makes a lot of sense, or inside the country, in which case you could just leave off the country code and let people look that up (and the instruction about dropping the zero) instead.

I would not suggest printing a block of 5 or more digits without some division into groups, though; it's just too hard to read, the other end of the spectrum from grouping them by twos. And in my experience, a hyphen isn't a recognized convention for an extension; I would probably assume that AGB's complete number was 12345678, and wonder why she had chosen to divide it in such an awkward place.

Sorry, I realize that doesn't provide a clear-cut answer, but I'm just not sure there is a clear-cut answer.

—> I suggest leaving out ...

I agree with hm about phone numbers from an American perspective. I would not guess that a number after a hyphen was an extension. I would assume it was a part of the phone number and dial it without waiting to be prompted for an extension number.

As for the grouping of digits, the area code (Vorwahl) should be grouped, then the phone number, then the extension. If possible, give those in groups of three or four. Most Americans are not at all used to seeing numbers in twos (with spaces) or groups of more than four.

The format of the number would vary, I think, depending on whether the card is being provided to Americans in the U.S. who probably don't have much international experience or Americans who are familiar with phone numbers abroad. For the first group, I would make the number look as much like an American number as possible. For the second, it wouldn't matter much.

I'm looking on my business card (Australia)

(+61) 08 1234 5678

> I would assume it was a part of the phone number and dial it without waiting to be prompted for an extension number.

Das ist kein Problem, du kannst die Nummer durchwählen. Die Zeiten, in denen erst eine hauseigene Vermittlungsstelle anspringen musste, sind lange vorbei.

@hm--us:

Ich kenne etliche Menschen, die mit der weggelassenen 0 nicht zurechtkämen. Was das angeht, mit der Landesvorwahl kämen sie erst recht nicht klar.

Wir reden hier aber wahrscheinlich über zweisprachige Karten. In diesem Fall würde ich empfehlen, die deutsche Seite mit 0, ohne Landesvorwahl, und die internationale Seite mit Landesvorwahl, ohne "0", zu gestalten.

Was das Gruppieren von Ziffern angeht: Vielleicht kann hier jemand mal einen Blick in ein britisches Telefonbuch (oder die "gelben Seiten") werfen, und sich ein großes Unternehmen rauspicken, die eine selbst gestaltete Anzeige haben. Die müssten es ja "richtig" machen, oder?

In the UK the usual way to write a telephone number is:

+44 (0) 1794 334566
or
+44 (0) 23 8060 7888

In each case, the area code is the first group after the +44 (0). However, the area codes are of two types, either five digits beginning in 01 or three digits beginning in 02. Mobile numbers always have a code beginning 07xxx, and special rate numbers begin 08xx.

If the country code is omitted, the area code is written in full.

In each case, only the actual number after the area code has to be dialled if the caller is in the same area as the number being called.
The reason that numbers with area codes beginning in 02 are written in two groups of four is probably that a group of eight numbers is rather too long to read easily.

I just had a look at my business card (UK).

I can confirm tengun's point of view. The format of the number on my business card is +44 (0)20 1234 5678. The Extension is not clearly separated, because the number of the switchboard is + 44 (0)20 1234 5000.

I have also looked at some business cards I got from people in other companies and the pattern is the same regarding country code and area code and actual number (actual number in two groups of four).