Classical phonetics included phonology. You were doing phonology if you were considering how sounds function in a language. Although the Classical Phoneticians spoke of the phonetics and phonology of this or that language, you can see that in a sense phonetics can be thought of as about the universal properties of speech sounds and phonology as about more the language-specific functional properties of sounds. Important Points of Classical Phonetic Theory Speech is segmental in nature. An utterance is a string of concatenated sounds.
Speech sounds are permutable.
That is, they can be substituted in strings to alter the meaning. Speech sounds can be 'captured' in a symbolic representation using an alphabet system. This can be refined to enable all relevant detail to be put onto paper. Sounds can be classified and shown to form systems. Once identified each subset could be presented within the framework of a system of classification showing how the sounds relate to each other on an articulatory basis.