Samuel Morse's original code was designed for the landline telegraph service. It worked well with the mechanical sounders heard in the telegraph stations. However, with use, some characters we changed by various users in various countries.

In 1848 Germany created a standard which eliminated the long spaces and long dashes. The new standard also changed the code for the numerical characters. This modified version of the Morse code was accepted in 1865 throughout Europe and became known as Continental Morse. Later, as Continental Morse was accepted for use around the world, it became known as International Morse. The original version of Morse code became known as American Morse.

In 1912 at the Radiotelegraphic Convention meeting in London, it was decided that all radio signals would be sent using International Morse. Thus the confusion of various operators inter-mixing the two code was eliminated.