There is no one sign language that is universal among all deaf people.
Australian sign language (Auslan), like other true sign languages
around the world, is not based on the dominant language of the society.
Auslan has its own syntax and its own lexicon. It has its own way of
organising meaning, just as any other language has. Auslan has
grammatical rules, a semantic system and a phonological system like all
other sign languages. Auslan is based on two-handed signs and
incorporates a two-handed alphabet (fingerspelling). Around 10,000 deaf
Australians currently use Auslan as their community language.

http://www.betterhealth.vic.gov.au/