Theirs are small voices railing against a cataclysm of nature. Borne out of places such as Rockville and Hyattsville on waves of electromagnetism, they are taking part in a global, short-wave radio conversation dedicated to filling the communications void left by an earthquake that devastated Mexico City last week.

"K3JW, this is 4Z4AB in Tel Aviv. Are you ready for the next message?"

"Roger. Go ahead."

"Telephone number 584-9455. See if Axelrod family is safe. Axelrod -- spell it Alpha X-ray Echo Lima Romeo Oscar Delta -- Axelrod. Their son is worried."

In his Rockville home yesterday, James Weitzman's radio speaker crackled with these and other messages. The 38-year-old communications lawyer, who became a ham operator when he was in his teens, was on the "K3JW" end of conversations bringing emergency aid and relief to earthquake victims thousands of miles away.

His transmissions and others like them are part of a sprawling and largely improvised network linking Mexico City with the rest of the world. Traditional communication links to the city have been largely destroyed, so it is up to amateur radio enthusiasts such as Weitzman, his 65-year-old ham radio cohort David Wharton in Hyattsville and others around the globe to patch the Mexican capital back into the world community.

The conversation between K3JW in Rockville and 4Z4AB in Tel Aviv, recalled by Weitzman yesterday, represented only the first part of the process tying the outside world to Mexico City.

In this case, a worried relative in Tel Aviv was inquiring about someone in the Mexican capital. After receiving the Mexico City telephone number of the Axelrod family, Weitzman radioed it to a ham operator in Mexico City, who would then dial the phone number.

Many local phone circuits in the devastated city are working, so if someone answers the phone the status of the situation can be readily ascertained, then radioed back to Weitzman, who would relay it to Tel Aviv. If there is no answer, the situation remains unknown.

"It gives me goose bumps," Weitzman said of the amateur radio operators' role in the drama. "This is the moment that we have trained for."

In Hyattsville, Wharton, a native of Lithuania and a survivor of Nazi concentration camps, has devoted his retirement years to his radio hobby. When the earthquake struck Thursday, Wharton became a full-time conveyor of terse communications that give a phone number and a person's status.

Wharton said he has received many telephone calls from friends and relatives of Mexico City residents. He takes down the information and radios it to his contact there, a ham operator called Shimon, who has a particularly strong signal.

While Wharton sat glued to the radio yesterday listening to Shimon, his wife Bassia commented that people "are tearing him up . . . . They call from everywhere -- Europe, Philadelphia, New Jersey. He spends all his time at the radio."

Wharton, who estimated that Shimon and his family are able to pass as many as 800 messages in one day, said that a half-hour after Mexico's second quake, he was receiving details.

With communications systems into Mexico not functioning fully, Wharton and Weitzman were asked yesterday to help link Mexican disaster workers with Israeli officials trying to send emergency supplies into the nation's hard-hit areas. They were asked to patch together any conversation that broke down over the long distance.

Weitzman, with his 110-foot radio tower pointed toward Israel, repeated the Israeli side of the conversation into a phone dialed to Wharton's home in Hyattsville. Then Wharton, who had his somewhat smaller antenna aimed at Mexico City, patched Weitzman's voice from his phone directly into his radio set, which transmitted the message to Mexico.

When the conversation ended, Mexican officials knew when the Israeli military transport plane would arrive early today with emergency supplies, what frequency the crew would be broadcasting on and what equipment would be needed for unloading. Included in the cargo is sophisticated extrication equipment the Israelis have developed for use in collapsed buildings.

Only in such an emergency would military officials employ civilian channels in this way. "Normally, they wouldn't use these frequencies or use overt language," Weitzman said. "But because of the breakdown of communications with Mexico, they are doing it."