VoIP Software Tools

By Neil Zawacki
Updated: April 08, 2011

VoIP (Voice over Internet Protocol) is a popular method for small businesses to make and receive phone calls over the internet. The system requires software to be downloaded onto the computers and softphones in order to function, as well as special programs on servers that are hosting the service.

Here’s how the software works:

A person speaks into a softphone or microphone that is attached to their computer. The software automatically processes this and converts the sound into a sizeable number of data packets. This is a general unit of digital communication that includes the source IP address, destination IP address, and sequence number. It then thoroughly encrypts the data packets so they can’t be heard by anyone who intercepts them, either intentionally or inadvertently.

With this complete, the software transmits the data packets across a high speed internet connection to the other user. The software then decrypts the information and converts it back into the original audio signal. If any of the data packets have disappeared, the software can usually reconstruct the signal by analyzing the sequence number of the previous and subsequent data packets.

It should be noted that the software will function differently based on whether you are talking to someone on a computer or a standard telephone line. If the person is on a computer, you will both need to have a “SIP” number. This is a type of signaling protocol that will provide the software with your current IP address and allow both computers to connect. The software requires this because most IP addresses are not static and tend to change every time the user logs in.

If you are calling a traditional phone line, a VoIP gateway will be required. The software on the media server will carry out the switching functions and convert the digitized signal to an analog signal, thereby allowing it to work with the PSTN (Public Switched Telephone Network.)

Some VoIP software, like Skype, uses a peer-to-peer system to contact the other user. The overlay network builds a table of available nodes (made up of the IP address and port number) and stores them in the Windows registry. The software then uses this information to make and receive phone calls and distribute bandwidth at different levels between users.

Keep in mind that the software will perform this function even if you aren’t making a phone call. Your computer will store the IP addresses of different users that can be utilized by other people making phone calls. This doesn’t tend to slow down the actual computer since no voice signals are actually sent.

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