Cisco and Motorola are not interested in this market, and Lucent is no longer American. To answer your question: maximizing shareholder value is why there are no US vendors (that in turn, might be because of lack of competition behavior between Verizon and AT&T leading to lowered investment in infrastructure)
>Yet Europe is home to two of the world’s leading vendors, Ericsson and Nokia; Samsung offers yet another alternative from a trustworthy democracy.