Bugles and post horns, like trumpets and hunting horns, were used to illustrate certain actions. However, they had a more limited musical range of notes and were used in a different social context.
The calls of the post horn were specific to the functions of the mail coach or to situations affecting a messenger on horseback. They were used to signal arrival or departure, overtaking or meeting of another carriage. These signals could also indicate how many horses and what kind of carriages were being used. They also served to indicate an emergency.
The post horn was limited almost exclusively to German­ speaking areas. The earliest set of calls unique to the post horn was recorded in Prussia in 1828.

In England, the coiled horns were replaced by straight-built metal horns known as 'coachhorns.'
Originally, the post horn could only play one or two harmonics. Late 18th century instruments could rise to the 6th or 8th harmonic. A further improvement was made in the 19th century by using fingerholes, keys or valves.
The characteristically pleasant timbre of the instrument inspired the French instrument maker Halaryto incorporate valves in the 'post-horn des allemands.' This 'cornet a pistons' appeared in Paris around 1828. This instrument was to become very popular in the 19th and 20th centuries.

Bugles were used primarily for military purposes. Modifications in the basic design led to the development of new instruments in the 19th century. The sound of the new keyed bugle, patented in London in 1810, was highly regarded even in orchestras.
The soprano bugle, developed in the German-speaking areas, represented a further modification of the original design; it was fitted with valves. This very popular instrument became also the precursor of the alto horn and the tenor horn.