I am getting tired complaining and explaining the difference between 00 and a + in the telephone and fax numbers. It’s quite simple actually and I wonder why the mistake is so frequent. So, here it goes in written form, so that I won’t have to explain it anymore – just provide a URL.
If you are writing phone number as 0035799513109, you are doing it wrong. It works for some, but not for everyone. 00 in this case is international dialing code. Many countries are using 00 for international dialing code, but not all of them, by far. For example, in Russia, the international dialing code is 810. So the phone number should be 81035799513109, not 0035799513109. See?
So, how are you supposed to know all these codes for each country and how are you supposed to provide your phone number so that anyone in any country can dial it and get where they are supposed to? The answer is simple: use ‘+’ for the international dialing code, followed up by the country code, and then the rest of the number. Each telephone company in every country will replace the plus in the beginning of the phone number with the appropriate international dialing code. Write the phone number as +35799513109. This will always work. And where it won’t, the person will at least know what to do with the number.