Copper-wire phone networks were built to withstand hurricanes and floods – but not wireless.

The proportion of inoperable cell sites reached 25 percent in areas affected by Hurricane Sandy, the FCC has reported.

The impact is considerable, as nearly 40 percent of American homes have cut wired landline phone service for wireless-only. Only about 10 percent of Americans have just landline service, according to communications service trade group US Telecom.

“Copper-wire phone networks were built with stability and dependability in mind because they were public utilities and were supposed to withstand hurricanes and floods,” said Harold Feld, a senior vice president at public interest group Public Knowledge.

Areas affected by Hurricane Sandy were slowly seeing cellular phone, Internet and television service restored, according to the FCC. However, according to Thursday morning data released by the FCC, nearly 19 percent of cell sites were still not working.