Field phones were produced for the needs of the Estonian army from the second half of the 1920s. These phones represented the evolution of the German hand-cranked generator devices of the First World War.

To make a call, the caller must crank the handle of the generator sending an electric current through the communication line to the receiving device, thus making it ring.

The phone’s components were mounted onto a wooden deck and placed inside a wooden box. On the top exterior part, there is a telephone handset with a plug, clamps for connecting telephone wires, a shunt button and a grounding terminal. The inside of the lid contained a diagram of the device and technical labels, as well as a mount for the crank handle and a sponge to keep the handset tightly pressed inside when the lid was closed. The device could be carried strapped over the shoulder. The leather shoulder strap had special fasteners on the outer sides of the box. These phones were powered by two 1.5-volt batteries.

In the 1930s, the Finnish army showed interest in Estonian field phones, due to logistical convenience and relatively low cost of the devices. During the 1930s, the Finnish army was mainly supplied with the model presented on display, which they named Tartu P-1-8.

During the First Soviet-Finnish War of 1939–1940 and later the Second Soviet–Finnish War of 1941–1944, the Tartu telephone was central to the system of field communication of the Finnish army despite there being other models in the supply. They were used in trenches, in front-line dugouts, in the headquarters of divisions and corps, and finally in rear facilities.

There were two types of this device produced for Finland: for land and naval use. The latter was distinguished by a triangular-shaped lid and the absence of grounding. Following the end of hostilities, these phones continued to be used by the Finnish army, as they were repaired, refurbished and updated. During the 1960s and 1970s, the devices were sent to conservation, thus remaining in the supply system of the Finnish army to this day.

The field phone on display was produced by the Tartu Telephone Factory in Estonia in the early 1930s.