As for the coding of language goes, there are sign language, cued speech, oral (speechreading and speaking) and total communication (a combination of a few or all modes). Sign language is not international, and varies throughout the country. Also, sign language has several methods such as ASL, SEE, CASE and PSE. There is also Rochester Method, but I haven't met anyone who uses that method.
As far as technology goes, here in Utah, we use mostly Videophone which is like a webcam connected to a TV and high speed cable line. It is like video conferencing, and also Video Relay Service is provided through Sorensen. It is the most popular choice of technology here in Utah. As for these who doesn't have Videophones, they use TTY/TDD which is like a typewriter connected to a telephone. In some countries, Deaf people prefer to use fax machines for communication. Also, the internet and instant messaging is a very popular way to communicate between deaf and hearing people without the middleman interference (relay).