Talk:Digital telephony

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)