...
You have to choose your hardware configuration to meet your network's needs. You can decide on the performance you need your sever to be capable of by considering the maximum number of concurrent calls you expect to have be made on the said server. The general formula is that for every concurrent call (with a ulaw codec - G711), you server will use up
...
Another way of figuring out what you server will have to stand up against is the total number of extensions on it. For example, if your server will provide VoIP for residential clients, most extensions will probably be phone terminals that do not require plenty of many resources. On the other hand, if you resell towards businesses, IVRs, Queues and other costly extensions will need a more powerful hardware configuration.
...
Another issue that needs to be addressed is that of connecting your server to a public telephone network. This becomes of your concern especially when your server is in-house. To connect to such a network you will need a physical gateway that routes and translates calls between the two networks for the VoIP user. The telephone company provides one or more trunk lines to the customer for connection to the customer's PBX.
...
Codecs are designed to enhance VoIP calling sound quality. However, these codecs influence your server’s or your network’s performance.
As an example, G711u and G711a do not compress packages upon sending them. This means that your call quality will improve, but they consume bandwidth. On the other hadehand, if you use G729 – which is one of the most used codecs – the packages will be compressed and you your call quality will be amplified, but this action consumes a greater amount of CPU.
A fair conclusion is that you should always calculate your system to have at least 30% resources free most of the time, so that you won't have to worry about peaks.
...
VoipNow is a platform that includes an IP PBX, billing engine, a browser interface and multi-tenant management. At the core of the VoipNow system lays the IP PBX, or Internet Protocol Private Branch Exchange, which is a private telephony network used within a company. It is a software application that implements the basic functions of a traditional hardware PBX as well as next generation digital services. Basically, it acts like an automatic switchboard that connects users. In addition, it offers new services that traditional telephony doesn't have the technology to.
...
For a more familiar experience, you can purchase IP phones or even use regular phones. The main function of the phone terminal is to transform analog audio signal into digital and vice-versa. IP phones are built to do this, but regular phones can also be connected to a VoIP network using a VoIP adapter.
...