Talk:Digital telephony

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This is an important subject of both current and historical importance, that can become a major article. Here's a skeleton for a more detailed article:

  • early experiments with PCM telephony
  • the 8-bit, 8kHz standard
  • DS0 as the basic digital telephony bitstream standard
  • non-linear quantization: A-law vs. μ-law, and transcoding between the two
  • bit error rate and intelligibility
  • first practical systems put into service
  • the U.S. T-carrier system, and the European E1-based system developed to carry digital telephony
  • introduction of space-time switching in fully digital telephone exchanges
  • replacement of tone signaling with digital signaling for trunks
  • termination of DTMF traffic at exchanges
  • in-band signaling vs. out-of-band signaling
  • the problem of bit-robbing
  • development of SS7
  • emergence of fiber optic networking allows greater reliability and call capacity
  • transition from plesichronous transmission to synchronous systems like SONET/SDH
  • optical ring networks further increase reliability
  • digital/optical systems revolutionize international long-distance networks, particularly undersea cables
  • digital telephone exchanges eliminate moving parts, make exchange equipment much smaller and more reliable
  • separation of exchange and concentrator functions
  • roll-out of digital systems throughout the PSTN
  • provision of intelligent network services
  • digital speech coding and compression
  • speech compression on international digital trunks
  • phone tapping in the digital environment
  • introduction of digital mobile telephony, specialized compression algorithms for high BER
  • voice over ISDN: direct digital termination to customers
  • the effects of digital telephony, and digital termination at the ISP, on modem performance
  • voice over IP as a carrier strategy
  • emergence of ADSL leads to voice over IP as a consumer product
  • convergence of VoIP, mobile telephony, etc.
  • flattening of telephone tariffs, increasing moves towards flat-rate pricing as the marginal cost of telephony drops further and further

-- Karada 23:03, 29 October 2005 (UTC)