Original: There are 18 internet service providers located in the capital of North-Rhine Westphalia . With two of the four big German providers of mobile frequencies , D2 Vodafone and E-Plus , DÃ 1\/4 sseldorf leads the German mobile phone market .
Simplified: Two of the four leading mobile phone companies of Germany have their seat in DÃ 1\/4 sseldorf like 18 internet providers and more than 400 advertising agencies .