How do you relay the digits of a phone number? For example:
Frau Stein: „Wie ist ihre Telefonnummer?“
Udo: „Sie ist 0451-83794.“
Do you say the phone number digit by digit or do you group them in some way and what is the norm?
There is no general rule, but I once heard that secretaries in Germany learn to spell out phone numbers digit by digit for a good reason: In contrast to other languages, German “switches” the order for numbers greater than 12.
While in English, for example, you say twenty-four for 24, in German it would be Vier-und-Zwanzig. That could lead to problems for people writing down the number while you speak. As 24 in spoken German starts with Vier, they might write down 4 instead of 2 and would have to make a correction.
It is good practice, however, to group the numbers while speaking. For example, 09887–1234567 could be read as:
Null Neun Acht Acht Sieben ... Eins Zwo Drei ... Vier Fünf ... Sechs Sieben.
The worst case: A colleague of mine always gave his phone number like:
Null Achthunderfünfzig Siebhundertdreizehn Acht Vierundzwanzig
(random number here, but you get the picture). The person on the phone would never know if Achthundertfünfzig was supposed to be 850 or 80050. Same for Siebenhundertdreizehn.
The easiest, least fail-likely and safest way to pass on a phone number in speaking is to go digit by digit. Typically, the entire area code will be given at once, and then two or three digits given at a time; between each group the speaking party typically waits until the receiving party confirms by mhm or ja. (Unfortunately, one cannot easily identify area codes by number of digits as in the US. Very large cities have two digits, smaller but important ones three and small places four, always without the leading zero. Mobile numbers often have three, but sometimes four.)
Null, acht, acht, zwo, eins, – neun, drei, null, – zwo, fünf, null.
Note that to prevent confusion, the digit 2 is often given as zwo rather than zwei.
There is no rule stating that the number should be given exactly in that way and not in groups of two (neun, drei, – null, zwo, – fünf, null). However, in exactly this case I am used to the number being given like this, because it is a radio station’s number they frequently relay in this way on air.
Some people also use groups of two and turn those into two-digit numbers. In that case, the same number would be given as:
Null, achtundachtzig, einundzwanzig, – dreiundneunzig, null zwo, fünfzig.
Note that 02 becomes null zwo rather than just zwo (or zwei. The two are replaceable). The area code’s leading zero is always given as a separate zero. In case the number of digits is odd, one digit is chosen seemingly at random and given as a single one. So the area code of Weilheim in Oberbayern can be given as one of the following:
Null, achtundachtzig, eins.
Null, acht, einundachtzig.
Some people go even further and include hundreds (i.e. groups of three) into their counting. But I would argue that that is the rarest case nowadays.
The problem with counting hundreds is that you can never be entirely certain whether the above is 0881, 080081 or 0810081 (achthunderteinundachtzig, achthundert einundachtzig and acht hundert einundachtzig, respectively).
My cousin was once told to relay a phone number from upstairs (where her father said it to her) downstairs to me. There were three people and we arrived at three different phone numbers due to the difficulty of keeping track with three-digit numbers. So avoid those if you can.
Usually it is read number by number, nonetheless there are regions, where it is common to read numbers pair-wise, but then you have to be careful with leading zeros.
Spontaniously, I would speak out the number before the dash one by one and the ones after by pair, leading to:
0 4 5 1 – 83 79 4
Null Vier Fünf Eins – Dreiundachtzig neunundsiebzig vier