The first experiments on long distance telephone connections were conducted in Russia by the military. In the army, the testing of telephone devices that appeared in the country in late 1877, was entrusted to Colonel V.B. Jacobi.
A Russian military engineer and inventor, V.B. Jacobi was the son of the St. Petersburg Academy of Sciences scientist B.S. Jacobi, himself the creator of the electric motor, as well as the first electrotyping machine.
Having received education at the family home of the academic Struve and then special education at the Nicholas School of Engineering, V.B. Jacobi joined the Caucasian Battalion of Technicians. He then served in the Engineering School, where he was appointed as Commander of His Highness the Grand Duke Nicholas (senior) battalion. V.B. Jacobi was later seconded to the Technical Galvanic Institution. He was an active member of the Imperial Russian Technical Society in the Photographic and Electrical Department.
In 1878 V.B. Jacobi established telephone communication between two islands in the Trångsund Strait over a distance of 7 km and then, in Finland, a military airline telegraph over a distance of about 30 km.
After testing many field telephones, which were bulky and weighed about 22 kg, Jacobi invented a portable device (1881), intended for military field communications and named it the 'Telekal'. Essentially it was a vibrating telephone signal device.
In 1882 the Telekal was successfully demonstrated at the 2nd St. Petersburg Electrotechnical Exhibition and was later tested at the Nikolayev railway.
Jacobi was adamant that soldiers could be trained in handling these phone devices with ease and in the shortest possible time. And he was right!
Another famous invention of V.B. Jacobi was the mikromikrofon.
V.B. Jacobi died in poverty in August 30, 1884.