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PSTN, or Public Switched Telephone Network, is the traditional system of telephone communication that has been in use for over a century. One of the key components of PSTN is the use of codecs, which are used to compress and decompress audio signals for transmission over the network.

There are several different codecs used in PSTN, each with their own unique characteristics and applications. Some of the most commonly used codecs include:

  • PCM (Pulse Code Modulation): This is the most basic codec used in PSTN and is used to digitize analog audio signals. PCM is a lossless codec, meaning that no information is lost during the compression and decompression process.
  • ADPCM (Adaptive Differential Pulse Code Modulation): This codec is similar to PCM but is designed to improve the efficiency of digital audio transmission. ADPCM uses differential coding, which means it only transmits the difference between consecutive samples, rather than the entire sample.
  • G.711: This is the standard codec used in PSTN and is used to compress and decompress voice signals at 64 kbps. G.711 is a lossless codec and is widely supported by most PSTN systems.
  • G.726: This codec is used to compress and decompress voice signals at rates of 40, 32, 24, and 16 kbps. G.726 is a lossy codec, meaning that some information is lost during the compression and decompression process.
  • G.729: This codec is used to compress and decompress voice signals at 8 kbps. G.729 is a very efficient codec and is often used in applications where bandwidth is limited.

Conclusion:

Codecs play a crucial role in PSTN, they are used to compress and decompress audio signals for transmission over the network. There are several different codecs used in PSTN each with unique characteristics and applications. Some of the most common codecs used include PCM, ADPCM, G.711, G.726, and G.729.

Frequently Asked Questions and Answers:

What is PSTN?

PSTN stands for Public Switched Telephone Network, it is the traditional system of telephone communication that has been in use for over a century.

What are codecs used for in PSTN?

Codecs are used to compress and decompress audio signals for transmission over the PSTN network.

Is PCM a lossless codec?

Yes, PCM is a lossless codec, meaning that no information is lost during the compression and decompression process.

Which codec is the standard codec used in PSTN?

G.711 is the standard codec used in PSTN and is used to compress and decompress voice signals at 64 kbps.

Is G.729 a efficient codec?

Yes, G.729 is a very efficient codec and is often used in applications where bandwidth is limited.