Phone Systems

1. Phone Systems Overview of Communication Matthew Whited

2. Brief History • 1840: Samuel F.B. Morse & Alfred Vail were granted patent for first practical telegraph • 1876: Alexander Graham Bell was granted patent for telephone • 1877: Bell offered to sell telephone to Western Union for $100,000 • 1885: AT&T formed as a subsidiary of American Bell • 1893: Heinrich Hertz, detected first radio waves • 1896: Guglielmo Marconi invented the radio • 1912: Lee de Frost invented the vacuum tube • 1924: H. Nyquist developed the “telephotography” machine • 1946: First Mobile Phone Call (AT&T) • 1947: William Shockley, John Bardeen, and Walter Brattian invent the transistor • 1960: First Communication Satellite “Echo 1” (Passive Reflector / NASA) • 1960: First Active Repeater Satellite “Courier 1B” (Philco) • 1962: First Private Funded Communication Satellite “Telstar” (AT&T) • 1973: Martin Cooper invents first personal mobile handset • 1988: TDMA is developed by CTIA (Cellular Technology Industry Association)

3. Brief History

4. Brief History Echo 1 (NASA)

5. Telstar Courier-1A Brief History

6. Media • Interfaces • Analog • Digital • Cellular • Switching

7. Interfaces • Standards Groups • RJ (Registered Jack) • OC (Optical Carrier) • RS (Recommend Standard)

8. Standards Groups • USOC (Universal Service Order Code) • ANSI (American National Standards Institute) • EIA (Electronic Industries Alliance) • TIA (Telecommunications Industry Association) • ISO (International Standards Organization) • IEEE (Institute of Electrical and Electronics Engineers) • ITU (International Telecommunication Union) • CCITT (International Telegraph and Telephone Consultative Committee| Comité consultatif international téléphonique et télégraphique) • OSI (Open Systems Interconnection)

9. RJ (Registered Jack) • http://www.arcelect.com/RJ_Jack_Glossary.htm • Indicator Letters • C: Flush Mount • W: Wall Jack • S: Single Line • M: Multi-line • X: Complex-Line • RJ-11C/W: Standard Phone Jack • 6 or 4 pin, 3 or 2 pair • Pin 3/2: Ring • Pin 4/3: Tip • RJ-12C/W • 6 pin, 3 pair • Pin 3: Ring • Pin 4: Tip • RJ-45C/W • 8 pin, 4 pair • RJ-48X (SmartJack) • T1

10. RJ (Registered Jack)

11. OC (Optical Carrier) • OC-n Mbps = n x 51.8Mbps • SONET (Synchronous Optical NETworking) • OC-1: 51.8Mbps • OC-192: 9945.6 Mbps

12. RS (Recommended Standard) • DTE (Data Terminal Equipment) • DCE (Data Communication Equipment) • RS-232 a.k.a. EIA323 / TIA232 • Revision “C” set in 1969 • Point to Point • Standard Serial Interface on a Computer • RS-485 a.k.a. EIA485 / TIA 485 • Point to Multi-Point

13. RS (Recommended Standard)

14. Analog • POTS (Plain Old Telephone Service) • PSTN (Public Switched Telephone Network) • Tip/Ring

15. Analog

16. Digital • Frame Relay / X.25 • Leased / Dedicated Lines • ISDN (Integrated Services Digital Network) • T/E Carriers • ATM (Asynchronous Transfer Mode)

17. Frame Relay / X.25 • Packet Switching Network • Virtual Circuits • Connects to a semi public cloud or “Frame” • Typically pay for usage • Typically configured as Point to Multi-Point • Slower then dedicated service

18. Leased / Dedicated Lines • Point to Point • Typically pay for mileage (tariffs)

19. ISDN (Integrated Services Digital Network) • B: Bearer 64k (Data or Voice) • D: Data 16k (Control) • Can be Channelized • PRI (Primary Rate Interface) • T1: 23B+D (US/Japan) • E1: 30B+2D (Everyone Else) • BRI (Basic Rate Interface) • 2B+D

20. T/E-carriers • DS (Digital Signal) • DS0: 64kbps • T1: DS1 = DS0 x 24 • T2: DS2 = DS0 x 96 or DS1 x 4 • T3: DS3 = DS0 x 672 or DS1 x 28 • T4: DS4 = DS0 x 4032 or DS3 x 6 • E1: DS0 x 32 • E2: DS0 x 128 • E3: DS0 x 512 • E4: DS0 x 2048

21. ATM (Asynchronous Transfer Mode) • Uses TDM and PCM • Cells instead of frames • Reduced jitter caused by multiplexing

22. VoIP (Voice over Internet Protocol) • NVP (Network Voice Protocol) • NBX (Network Branch Exchange) • SIP (Session Initiation Protocol) • H.323 • IAX2 (Inter-Asterisk eXchange) • SCCP (Skinny Client Control Protocol)

23. NVP (Network Voice Protocol) • 1973 by Danny Cohen for ARPAnet • Outdated

24. NBX (Network Branch Exchange) • 3Com • POSIX (Real-time Embedded UNIX) • Layer 2 Protocol • Can ride inside of IP Packets

25. SIP (Session Initiation Protocol) • Industry Standard • Allows use though 1 firewall • TCP and UDP ports 5060

26. H.323 • Example is Microsoft Netmeeting • Directly Support Video • Doesn’t like firewalls much

27. IAX2 (Inter-Asterisk eXchange) • Mark Spencer • Proprietary but Open • Low overhead • Designed with NAT and Firewalls in mind • Designed with Trunking and Multiplexing in mind • UDP 4569 • Based on SIP, MGCP, RTP

28. SCCP (Skinny Client Control Protocol) • Cisco • Windows Server

29. Cellular • Voice • Analog • Digital • TDMA (Time division multiple access) • CDMA (Code division multiple access) • GSM (Global System for Mobile Communications) • Data • GPRS (General Packet Radio Service) • EDGE (Enhanced Data rates for GSM Evolution)

30. Hide a Cell Tower Cellular

31. Switches • Store and Forward • Buffers transmission • May run checksum • Cut Through • Read only enough of the data stream to identify receiver • Fragment Free • Form of Cut though that checks that the receiver is available • Adaptive • Can automatically pick best method of switching for data stream

32. Plexes • Simplex • Paging Systems • Unidirectional • Half Duplex • PTT (Push To Talk) • One Direction at a time • Full Duplex • Phone • Both Directions at the same time

33. Encodes • Analog to Digital • TDM (Time-Division Multiplexing) • 64Kbps x 24 Channels = 1.536 Mbps • PCM (Pulse Code Modulation) • 8-bits x 8000 Hz

34. Codec (Coder / Decoder) • G.711 (Audio) • 56 or 64kbps • a-law / u-law • 8 bits compressed PCM • G.726 (Audio) • 16 to 40 kbps • Typically 32kbps • 100% savings in bandwidth over G.711 • G.729 (Audio) • May Require Licensing • 6.4 to 11.8 kbps • Typically 8kbps • MAJOR savings in bandwidth • Mostly used in VoIP • Compressed in 10ms chunks • Does not work well with Fax or DTMF • These can be send using G.711 or another form of “Out-of-band” communication

35. Modulation • AM (Amplitude Modulation) • 2400 baud max • 2 different samples • FM (Frequency Modulation) • 2400 baud max • 2 different samples • PM (Phase Modulation) • 4800 baud max • 4 different samples • QAM (Quadrature with Amplitude Modulation) • 38400 baud max • 4 phase x 4 bits x 2400 baud = 38,400 baud

36. Asterisk • http://www.asterisk.org • http://www.digium.com • Open Source • Works on Linux, BSD, and OS-X • Channels • Bluetooth • FAX • H.323 • IAX • ISDN • SIP • Skinny (SCCP) • Zap (FXS/FXO) • Pretty much anything else that does anything else

37. 3com NBX • Hopefully I can demo the Phone • NBX, Layer 2 • Can ride in IP

38. Other Definitions • AA – Automated Attendant • ACD – Automatic Call Distributor • CTI – Computer Telephony Integration • Dial Plan - “Routing” table for phone systems • DTMF - Dual-Tone Multi-Frequency • Extension – End station / Node • FXO - Foreign Exchange Office • Receiver • Modem • FXS - Foreign Exchange Station • Provides battery (power) • Send Dialtone • IVR – Interactive Voice Response • Latency – end to end delay • Lineman Handset – Analog Telephone Line testing device • a.k.a. Butt Set or Test Set • Basically a telephone with alligator clips instead of a plug • Loop – single telephone line

39. Other Definitions • PBX - Private Branch Exchange • SIM - Subscriber Identification Module • Trunk – Multiple Lines acting as one • TTS – Text to Speech • VM – Voicemail • FWD – Free World Dialup • Free VoIP service • Does not provide free PSTN • LEC – Local Exchange Carrier • ILEC – Incumbent • Existed before AT&T breakup (1982) • Baby bells • CLEC – Competitive • After AT&T breakup • Most noted are Cable TV companies that provide phone over cable (Most of these are NOT VoIP providers)

40. References / Helpful Web links • http://www.wikipedia.org • http://www.freeworlddialup.com • http://asteriskathome.sourceforge.net/ • http://www.nadcomm.com/timeline.htm • http://www.att.com/history/