From Stargate Wiki
A Radio is a communication device built and used by many different races.
Radios contact one another on different frequencies. Some have antennae and some have other features like headsets. Radio transmissions can be interrupted with intense interferrence from energy sources such as unstable wormholes. (SG1: "Children of the Gods", ATL: "Rising", "Underground", SGU: "Air, Part 1", "Incursion, Part 1")
The Genii have radio technology which they use to communicate with one another and with other races. They are two different types - a handheld larger version and smaller versions worn on the wrist. (ATL: "Underground", "Harmony")
The Manarians also have radio technology very similar to the Genii, so they may have traded for it. They are known to make contact with the Genii using these radios. The Manarians also make use of radio relay stations. (ATL: "The Storm")
The Tau'ri made use of radio technology as their primary communication method for offworld SG teams. These radios have a limited range. Each member of the offworld teams take a radio with them and use it to communicate with one another if they get lost or with Stargate Command through an open Stargate. Members of the Atlantis expedition use a headset connected to their radios which they wear offworld as well as on Atlantis. (SG1: "Children of the Gods", ATL: "Rising", "Hide and Seek")