Not sure, but is 189 possibly a cell phone provider prefix, like 0171 for example? Are there eight digits to the actual number or are there any digits that you did not express in x's?
What do you dial to get out of the country? In the USA you have to dial 011 to get out of the country. So it would be 011-49-89-personal phone. In Europe you dial 001 (mostly) to get out of the country.
Till