Technology – Internet Telephone Systems
A new alternative to traditional telephone networks has appeared in the last couple of years. It uses computers and computer networks to route voice calls over the Internet.
Telephone calling over computer networks using the Internet is called IP telephony, Internet telephony, or Voice over IP (VoIP). Networks transport not only ordinary data, but also carry a digitized voice signal along with routing data to establish the connection. In IP calling, a voice signal is transformed into digital impulses and sent over the network in the form of data packets.
At the receiving end, the packets are reassembled. The data transfer is regulated by the so-called IP protocol. Calls can be made using special IP telephones or by computers equipped with special software. Ordinary telephones also have the capability to be connected to the system when they are fitted with IP adapters. Making phone calls over a computer network can often result in significant cost savings for the user, and even the ordinary telephone network can be accessed using VoIP gateways.
A user’s computer or IP telephone is identified with an IP address. One problem is that the caller’s IP address must be known but this can be subject to frequent change. The solution to this problem is that the VoIP system contacts a special server with their user identification. They then transfer the relevent IP address details and set up the connection. In this way users are not tied to a particular computer or phone line and can be reached at any location with an Internet connection.
Reception quality
At the receiving end, the data packets formed from the voice signal are assembled in a specific order. However, when data packets arrive too late at the destination device, they can no longer be integrated into the voice stream, which leads to a perceived drop in the call quality
This transmitting of voice signals in data packets presents quite different challenges in comparison to those involved in the transfer of ordinary computer data, for instance the data transfer rate must be sufficiently high to ensure good quality.
SECURITY ISSUES
Internet telephone systems allow an exchange of data, like any other Internet connection. This allows for unauthorized access to communications; for example, a call may be monitored or diverted.
Although encryption is possible, it can reduce sound quality. As with e-mail, spam, or advertisements can also be received.
BASICS
WITHIN ORGANIZATIONS and businesses, increasing numbers of IP telephone networks are being established.
IP CALLING maybe limited to a network or location, but thanks to the Inter net. it can also be used worldwide