This is probably one of the questions most frequently asked by those who are new to the world of Asterisk. The answer depends largely on what we are going to do with our system.
Conversations that bridge between codecs (called transcoding) take maximum power to handle. Voice over IP conversations seem to take a little more processing power than straight Time-Division Multiple-Access (TDM) calls. Having our server run scripts to find information will take more power than if we define everything statically. How many different conversations we have going at a time will affect how much horsepower we need our server to have as well as the features we use.
Do you see the complexity of answering this question? We have to figure out what we are going to use before we can figure out how big a server we will need. That said, there are some good rules of thumb we can start off with.
First, while we can run an Asterisk server on an old Pentium 90 with 64 MB of RAM, why would...