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Meeting Dates for 2022
.

We still need your suggestions for possible topics please let us know what you would like us to
try and put an together for future meeting. We have currently run out of ideas for next year
so please give it some thought and let us know what your ideas are.

24th August 2022 Voice over I/P

21st September 2022 Chrome Books

19th October 2022, Databases

16th November 2022 Photograph Improvement Tips

14th December 2022 Photo Competition

Last Month…

Alan Danbury introduced us to the world of “Voice Over IP”, the future of our telecommunication systems.

An Overview

Voice over Internet Protocol (VoIP), also called IP telephony, is a method and group of technologies for the
delivery of voice communications and multimedia sessions over Internet Protocol (IP) networks, such as the
Internet. The terms Internet telephony, broadband telephony, and broadband phone service specifically refer
to the provisioning of communications services (voice, fax, SMS, voice-messaging) over the Internet, rather
than via the public switched telephone network (PSTN), also known as plain old telephone service (POTS).

The steps and principles involved in originating VoIP telephone calls are similar to traditional digital telepho-
ny and involve signalling, channel setup, digitization of the analogue voice signals, and encoding. Instead of
being transmitted over a circuit-switched network, the digital information is packetized and transmission oc-
curs as IP packets over a packet-switched network. They transport media streams using special media deliv-
ery protocols that encode audio and video with audio codecs and video codecs. Various codecs exist that op-
timize the media stream based on application requirements and network bandwidth; some implementations
rely on narrowband and compressed speech, while others support high-fidelity stereo codecs.

The most widely used speech coding standards in VoIP are based on the linear predictive coding (LPC) and
modified discrete cosine transform (MDCT) compression methods. Popular codecs include the MDCT-based
AAC-LD (used in FaceTime), the LPC/MDCT-based Opus (used in WhatsApp), the LPC-based SILK (used
in Skype), ì-law and A-law versions of G.711, G.722, and an open source voice codec known as iLBC, a co-
dec that uses only 8 kbit/s each way called G.729.