What are the various protocols used?
There are two types of protocol for you to consider. The first is the telecomms protocol. The second is the audio coding protocol. These are explained below. Main Section ISDN Worldwide Protocols & interoperability ISDN is not quite the same all over the world. Telecomms providers in different countries (and in the US, in different states) may use slightly different ISDN protocols. When you buy a codec, you buy it with the correct type of Terminal Adapter installed. Some TAs can be switched to work with different protocols, others are fixed to one or a selection of them. This is only a case of you having the right equipment to connect to your line (rather like having a 110v or 220v toaster – you have to have the right power supply) it does not affect your ability to connect to other people who’s equipment may be connected to another protocol in another country. Having said that: there is one exception to this rule. In some parts of the states, there is still an older version of ISDN in
