Anyone who has ever opened a cellphone bill to find astoundingly high charges can empathize with Bob St. Germain. His bill was $18,000.

In 2006 St. Germain, 67, of Dover, Mass., began trying to get the charges lifted. He went through automated systems, live customer service, collection agencies and the media before his cellphone carrier removed the charges.

The Federal Communications Commission is considering rules to help prevent cases like St. Germain's. An agency survey showed that 30 million American consumers of cellphone and broadband service — one in six — have experienced what has come to be called "bill shock." Eighty-eight percent of those surveyed said the cellphone company did not contact them after their bill suddenly increased, and 84 percent said their cell carrier did not contact them when they were about to exceed their allotted minutes, text messages or data downloads.

Under rules being considered by the FCC, the companies would have to give consumers a heads-up when they are about to exceed their allotments or if their bill is about to increase.

In the case of St. Germain, his son ran up charges when he plugged his cellphone into a laptop to connect to the Internet. The son didn't know free Web access was no longer included after his father renewed the family plan.

In comments to the FCC, AARP legislative counsel David Certner said cellphones have "become an indispensable tool of modern life," and pointed to an FCC survey in which 22 percent of respondents who said they had experienced "bill shock" were over age 50.