GLOSSARY

codec 

Device or computer program for encoding/decoding a digital data stream or signal.

event

An entity that describes any activity on the monitored infrastructure. This could be CPU load increase, host down, or lack of memory.

jitter 

Stands for the variations between consecutive data packets arriving at the user's side. The lower this number, the better the voice quality will be. Skype has implemented a jitter buffer to ensure the uninterrupted communication.

Poor Call %

A measure used in the domain of Quality of Experience (QoE) and telecommunications engineering, representing overall quality of a stimulus or system. It is expressed as a single number in the range of 1-5, where 1 is the lowest quality and 5 is the highest.

packet loss

Often defined as a percentage of packets that are lost in a given window of time. Packet loss directly affects audio quality - from small, individual lost packets having almost no impact, to back-to-back burst losses that cause complete audio cut-out.

peer-to-peer (P2P) 

Computing or networking is a distributed application architecture that partitions tasks or workloads between peers. Peers are equally privileged, equipotent participants in the application. They are said to form a peer-to-peer network of nodes.

Public switched telephone network (PSTN)  

The aggregate of the world's circuit-switched telephone networks that are operated by national, regional, or local telephone operators, providing infrastructure and services for public telecommunication.

Quality of Experience (QOE)

Records numeric data that indicates the media quality and information about participants, device names, drivers, IP addresses, and endpoint types involved in calls and sessions.

round trip delay

Length of time it takes for a signal to be sent plus the length of time it takes for an acknowledgment of that signal to be received.  

session

An entity that describes the facts of the unified communication interaction. Users might have a point-to-point call or conference call with multiple parties. There are several session types:

• PTP (point-to-point)
• PSTN (Public Switched Telephone Network) 
• Conference

Session Initiation Protocol (SIP) 

Communications protocol for signaling and controlling multimedia communication sessions in applications of the Internet telephony for voice and video calls. List of SIP response codes:

• 1xx - Provisional responses to requests indicate the request was valid and is being processed.
• 2xx - 200-level responses indicate a successful completion of the request. As a response to an INVITE, it indicates a call is established.
• 3xx - This group indicates a redirection is needed for the completion of the request. The request has to be completed with a new destination.
• 4xx - The request contained bad syntax or cannot be fulfilled at the server.
• 5xx - The server failed to fulfill an apparently valid request.
• 6xx - This is a global failure, as the request cannot be fulfilled at any server.

Transmission Control Protocol (TCP) 

One of the main protocols of the Internet protocol suite. TCP provides reliable, ordered, and error-checked delivery of a stream of octets (bytes) between applications running on hosts communicating via an IP network.

User Datagram Protocol (UDP) 

One of the core members of the Internet protocol suite. With UDP, computer applications can send messages, in this case, referred to as datagrams, to other hosts on an Internet Protocol (IP) network.