May 16: Sichuan Amateur Radio Emergency Service Command Center Directors: Liu Hu (right) and Liu Xu.

They are amateur radio enthusiasts also known as "Hams". They initiated their relief efforts after the May 12 earthquake before other communication channels were back in operation in the quake-hit areas.

At 2:28 PM on May 12, a deadly quake struck southwest China's Sichuan Province, killing 69,181 people as of June 22 and leaving 18,522 people still missing.

Communications in many towns and cities broke down shortly after the earthquake. Mobile phones, land lines, and the internet were not accessible in the quake-hit areas.

The Sichuan Amateur Radio Emergency Service (SARES), a non-governmental organization of amateur radio enthusiasts, launched its relief efforts when the quake-hit areas lost communication channels. "Millions might be rescued through a successful exercise in short-wave liaison, and a portable radio station or vehicle station can play a significant role in the relief campaign," said Liu Hu, a head of the service network.

Radio Hams urgently mobilized for the relief campaign

The amateur radio enthusiasts are called Hams, and their passion is for upgrading radio station equipment to get better signals and voice traffic. Some are even more technically expert than the communications corps.

The nickname 'Ham' comes from the call sign for one of the first private radio stations, and was based on Hyman-Almy-Murray, the names of the three Harvard radio enthusiasts who set it up. An amateur radio (also known as Ham Radio) applies simple technology which ordinary people can use to send and receive messages by electromagnetic waves without the need for a cable connection.