Not really. In the US there are several sign language 'dialects' or 'languages'. American Sign Language (the US only), which is based on French Sign Language but different enough users cant really understand each other. Brits have British Sign Language which is again totally different. Then theres Nicaraguan Sign Language, Signed Speech, Cued Speech Sign Language, Sign Supported English, Finger Spelling, Pidgin Signed English, Padget Gorman Signed Speech, and International Sign. And thats all just in the USA (with the exception if International Sign). Other countries have their own sign language systems just as they have different spoken languages. There is no true international sign language save for International Sign and i believe that is used mainly for politics, like in the United Nations meetings.