Free Internet Phone Calls
Calls transmitted through VoIP, also called internet telephony, broadband phone or IP telephony, are often advertised as free internet phone calls. In these, the input, also called the analog voice signal, is converted into a digital signal. This is then compressed and transmitted through the internet protocol packets using the Internet as the medium of transmission. At the receiver's end, this packet is decoded and the output is again in the desired format.
VoIP service providers can be accessed through analog telephone adapters, which connect a telephone jack to the IP network. VoIP phones can connect to the VoIP network through Ethernet or WiFi. Alternately, a digital phone is software which allows calling from the computer without any separate hardware device.
Particularly for business applications, free internet phone calls really save expenditure on communication (variable cost) and infrastructure (fixed cost). For commercial application, it eliminates the need for distinct voice and data networks as it routes phone calls through already present data networks.
Other features of traditional telephonic systems such as conference calling, caller ID, call forwarding etc are also available in online calls, and operators do not charge extra for these facilities.
Voice over internet provides additional features not offered by traditional copper wire telephones. These are video conversation availability, parallel file, message and data exchange, access to the address book etc.
With encryption and authentication, the digital data stream, transmitted through a digital transmission system, offers a secure connection for communication.
VoIP systems also do not require much additional expenditure. A high speed internet connection is enough to use the facility.
However, free internet phone calls are not entirely free from vices. For one, the security is still questionable, especially in the absence of proper encryption. Communication of vulnerable data is still susceptible to interception by hackers, causing service interruption, harvesting of data, recording of conversations and misusing sensitive information. Sensitive data such as military communication and classified government communication is transmitted through Voice over secure IP (VoSIP), Secure Voice Over Secure IP and Secure Voice over IP, which are more protected channels of encrypted transmission through IP networks.
Firewalls and network address translators often hamper transmission for free internet phone calls. Apart from this, data transmission in the IP network takes place through the compression of digital information into small packets. The system is vulnerable to congestion and fixed delays as the data travels a distance after conversion into digital signal, and reconversion at the receiving end. They are also susceptible to power outages, and these cannot locate the geographical position of a network user. This makes it difficult to trace emergency calls and potentially dangerous operators.
Calls through VoIP routed to mobile carriers sometimes face difficulty in connecting, With GSM number portability least cost routing providers are not able to use the network route