Cell phone experts say call-crossing possible

Stephen Curran

Monday, June 24, 2002 | 11:09 a.m.

While the chances of one cell phone user intercepting another call and hearing a terrorist plot seem slight, the crossing of calls does happen, especially during peak usage, experts say.

Henderson resident Michael Hamdan reported such a call last week to the FBI, saying he intercepted a conversation on his cell phone in Arabic between two men who talked about how the "city of corruption" would be hit on the "day of freedom."

Because the frequencies cell phones use are close to each other, they cross signals in the same way two radio stations often do, causing one caller to overhear a conversation intended for someone else, Andrew Gross, service architect for Counterpane Internet Security in Cupertino, Calif., said.

When Hamdan, a naturalized U.S. citizen born in Lebanon, tried to call his wife, he began hearing the conversation before the phone started ringing, he said. Normally, that would indicate the intercepted call came from another cell phone, Gross said.

For the two calls to cross, Gross said, at least one side of the intercepted call would have to pass through the same Las Vegas tower Hamdan's attempted call did, which means at least one of the men on the line was in the Las Vegas area.

However, features such as call forwarding can force a call to pass through a far-away tower without either party being near it, he said.

"Call-crossing" is more likely to occur when call volume is at its highest, which can make it difficult to trace the origin of the crossed call.

"If a number of calls are going through a cell tower, it's more likely an interception could happen," Gross said.

Mark Siegel, a spokesman for AT&T Wireless, Hamdan's wireless provider, declined to comment on what might have caused Hamdan's cell phone to intercept the call, saying only that the company tries "to ensure the privacy of all its customers."

AT&T operates on what is known as a TDMA network, which operates both digital and analog platforms, said Sprint spokesperson Vicki Soares, who also declined to comment on what might have caused the signals to cross. Sprint operates on a purely digital network.