Codecs encode or decode a data stream to remove redundancies and improve transmission speeds. Lisa discusses digitizing a signal along with comparing the various codecs in the G.700 series along with characteristics such as bit rate and voice quality.
- [Instructor] We use the phone system…to communicate information.…While in a conversation, we must be able to hear…and understand what the other party is saying.…VoIP communication involves analog and digital communication…in that we speak in analog,…which is a continuous wave form.…In order for the signal to travel over a digital network,…we digitize and encode the signal.…
In this illustration, we see the flow of information.…An algorithm transforms the data…before traveling over an IP network,…and then it is decoded at the receiver end.…When making a decision on how to reproduce the sound,…there are two choices.…Recreate the sound as if someone were to hear it…as if they were sitting right next to the speaker,…or reproduce it in a range…that the brain is capable of hearing and understanding.…
As we see in this graphic,…the range of human hearing is between 20…and 20,000 cycles per second,…or 20 hertz to 20 kilohertz.…However, testing demonstrates a human can understand speech…in the frequency range between 300 and 3300 hertz,…
Lisa Bock compares the traditional Public Switched Telephone Network (PSTN) to VoIP, and discusses the framework and components necessary for VoIP to be possible. She reviews codecs, including characteristics such as bitrate and voice quality; protocols for setup, communication control, and data transport; and media gateways, signaling protocols, and intermediary systems such as translators and mixers. Lisa then reviews business integration and the importance of conducting a needs analysis and network assessment prior to implementation. Learn about the many value-added services UC can provide, such as integrating VoIP with email, billing, management software, and other customer management systems. Lisa wraps up with a discussion on how ensuring quality of service (QoS) in a VoIP network minimizes latency and jitter and the importance of VoIP security to prevent malware, impersonation, hijacking, and denial of service attacks.
- History and evolution of PSTN
- UC overview and components
- Gateways, including signaling gateways, translators, and mixers
- Integrating VoIP and UC into your business network