Erlang OTP I/O - A few questions

I have read one of erlang's biggest adopters is the telecom industry. I'm assuming that they use it to send binary data between their nodes and provide for easy redundancy, efficiency, and parallelism.

Does erlang actually send just the binary to a central node?

Is it directly responsible for parsing the binary data into actual voice? Or is it fed to another language/program via ports?

Is res开发者_如何学Goponsible for the speed in a telephone call, speed as in the delay between me saying something and you hearing it.

Is it possible that erlang is solely used for the ease in parallel behavior and c++ or similar for processing speed in sequential functions?

---

I can only guess at how things are implemented in actual telecom switches, but I can recommend an approach to take:

• First, you implement everything in Erlang, including much of the low-level stuff. This probably won't scale that much since signal processing is very costly. As a prototype however, it works and you can make calls and whatnot.

• Second, you decide on what to do with the performance bottlenecks. You can push them to C(++) and get a factor of roughly 10 or you can push them to an FPGA and get a factor of roughly 100. Finally you can do CMOS work and get a factor of 1000. The price of the latter approach is also much steeper, so you decide what you need and go buy that.

• Erlang remains in control of the control backplane in the sense of what happens when you push buttons the call setup and so on. But once a call has been allocated, we hand over the channel to the lower layer. ATM switching is easier here because once the connection is set you don't need to change it (ATM is connection-oriented, IP is packet-oriented).

• Erlangs distribution features are there primarily for providing redundancy in the control backplane. That is, we synchronize tables of call setups and so on between multiple nodes to facilitate node takeover in case of hardware failure.

• The trick is to use ports and NIFs post prototype to speed up the slower parts of the program.