The plus character "+" is used in front of the international dialing code
A space character separates the international code from the remaining digits
The remaining digits should be presented as a single block
An extension number should be separated from the main number by hyphen "-"
When indicating more than one telephone number, separate them using a slash
In this case the international dialing code of the following phone numbers can be omitted.
When indicating consecutive numbers in an abbreviated manner use a slash
Examples:
+49 12345678
+49 12345678-0001
+49 12345678/79/80/81
+49 12345678/+49 987654321 / +49 9988776655