University:
Massachusetts Institute of Technology
Course:
15.501/516 | Accounting
Academic year:

2023
Views:

236

Pages:

9
Author:

Jocelynn Galloway

Competition in Telecoms Recitation #1 Agenda • US Telecom History • Phone Network Overview • Networking Introduction Industry Structure Pre-1984: Bell System • AT&T: – 22 local Bell companies – Local, interstate and international long distance – Manufactured and sold central office switches, telephones, electronics – Yellow and white page telephone directories • Long-distance competitors (MCI, Sprint) – Owned long-distance networks, but not connection to the homes – Relied on local (Bell) companies for call termination – Numerous complaints filed about AT&T’s unfair practices 1974: Anti-trust suit against ATT, resolved in 1984 1984: Divestiture • 22 Bell companies transferred to 7 Regional Bell Operating Companies (RBOCs) • Local Access Transport Area (LATA): RBOCs - local & toll calling • AT&T: manufacturing (became Lucent) and long distance • Bellcore formed (owned jointly by RBOCs): administered numbering plans. Renamed to Telecordia and acquired by Science Applications International Corporation (SAIC) 1996: Telecommunications Act • Local competition opened up to long distance, cable, local access and utility companies • Unbundling of ILEC network • Creation of Competitive Local Exchange Carriers (CLECs) to compete with Incumbent Local Exchange Carriers (ILECs) Original RBOC Territories •SBC Communications •USWest •Ameritech •SNET (Southern New England Telecom) •BellAtlantic •BellSouth •Pacific Telesis •Nynex …and then Natural Selection Stepped In •Qwest •Verizon •BellSouth •SBC Communications Abbreviations • • • • • • • FCC: Federal Communications Commission LATA: Local Access Transport Area RBOC: Regional Bell Operating Company LEC: Local Exchange Carrier ILEC: Incumbent LEC CLEC: Competitive LEC IXC: inter-exchange carrier Abbreviations • • • • • • POTS: Plain Old Telephone Service PSTN: Public Switched Telephone Network PoP: Point of Presence PBX: Private Branch Exchange MoDem: Modulator/Demodulator ISDN: Integrated Services Digital Network Analog vs. Digital • Analog – Continuous signal (i.e. non-discrete) – Voice, like many real-world “things” are analog – Slower and more prone to errors (less efficient) • Digital – Discrete data – Most often binary (i.e. 1’s and 0’s) – Higher speed and more reliable • Analog ÅÆ Digital – Modems are an example of devices that make analog ÅÆ digital conversions Circuit Switched vs. Packet Switched • Circuit Switched – Dedicated connection between two parties – Communication process: • Setup • Communication • Tear-down – Advantage: consistent channel/bandwidth – Disadvantage: inefficient use of network resources • Packet Switched – “Packetized” and “addressed” data – Communications process: • • • • Sender formats data into packet(s) Sender sends data Network routes data Receiver receives data, re-organizes data and potentially sends acknowledgement – Advantage: better use of network resources – Disadvantage: less predictable communication delay