WEEK 8

REVIEW ABOUT VOIP

Voice over Internet protocol (VOIP) is the revolutionary technology relatively new though in the communication industry. VOIP is a method that converts the analog signals into digital signals and then converts back to analog signals upon reaching the destination. This is due to the medium that is used for the transmission i.e. the Internet. The packet switching is the digital mode of transmission. Traditional circuit switched networks are easy to implement but they are very costly.

Voice over Internet protocol requires (VOIP) a relatively high-speed Internet connection. A DSL connection is the right form of broadband connection that can work fine for voice transmission. During the conversion from analog to digital some extra information is added to the voice data so that IP should know what the packet encloses. Most of times a priority tag is added to voice packet which makes IP know that this is a voice packet and needs to be transmitted in priority of the data packets. Other techniques are used to provide Quality of Service (QoS) for the quality of the voice.

In IP the data that has to be transferred is divided into many small packets and reach the destination from different paths. At the destination they have to reorganize themselves in the right order. It happens with the voice packets as they are using the IP. In voice packets 160 bits are added by IP so that it can reach the destination (White, Curtis, 2002)

The Real Time Protocol RTP is also used. "It provides timing information that allows the receiver to reconstruct the original timing of the transmitted material in a way that identifies the content being sent, provides security, and notifies the overriding application of lost data." (Gilmer, 2004)

 

Moreover TCP that is used in the data transmission is no longer used in the voice transmission. UDP, User Datagram Protocol is used instead of TCP. By using UDP, we get the facility that we are no longer waiting for the acknowledgement of the information that is carried to the destination. This reduces much amount of time as the source doesn't has to wait for the confirmation from the receiving end and so continues to transmit voice without any stoppage. "It is useful in cases where one sender wants to send the same information to multiple receivers and is not too worried if some pieces get lost along the way." (Gilmer, 2004)

Since PSTN lines can only achieve around 56kbps, they are not suitable for this kind of communication. For that reason DSL and Cable modem are highly preferred as they can achieve more than 10mbps. Time delay can occur if the connection speed is less. So for real time conversation and removal of delay broadband Internet is required.

Still taking in the view that VOIP is a relatively new technology, it has drawbacks. Since it requires Internet connection so if the power goes off, so does the telephone connection. So for this proper settings must take place. "Sound quality and reliability are still not up to the level of traditional telephone service." (Trope & Royalty, 2004)