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Phone Systems Overview of Communication Matthew Whited 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

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phone systems

Phone Systems

Overview of Communication

Matthew Whited

brief history
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)
brief history4
Brief History

Echo 1 (NASA)

media
Media
  • Interfaces
  • Analog
  • Digital
  • Cellular
  • Switching
interfaces
Interfaces
  • Standards Groups
  • RJ (Registered Jack)
  • OC (Optical Carrier)
  • RS (Recommend Standard)
standards groups
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)
rj registered jack
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
oc optical carrier
OC (Optical Carrier)
  • OC-n Mbps = n x 51.8Mbps
  • SONET (Synchronous Optical NETworking)
  • OC-1: 51.8Mbps
  • OC-192: 9945.6 Mbps
rs recommended standard
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
analog
Analog
  • POTS (Plain Old Telephone Service)
  • PSTN (Public Switched Telephone Network)
  • Tip/Ring
digital
Digital
  • Frame Relay / X.25
  • Leased / Dedicated Lines
  • ISDN (Integrated Services Digital Network)
  • T/E Carriers
  • ATM (Asynchronous Transfer Mode)
frame relay x 25
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
leased dedicated lines
Leased / Dedicated Lines
  • Point to Point
  • Typically pay for mileage (tariffs)
isdn integrated services digital network
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
t e carriers
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
atm asynchronous transfer mode
ATM (Asynchronous Transfer Mode)
  • Uses TDM and PCM
  • Cells instead of frames
    • Reduced jitter caused by multiplexing
voip voice over internet protocol
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)
nvp network voice protocol
NVP (Network Voice Protocol)
  • 1973 by Danny Cohen for ARPAnet
  • Outdated
nbx network branch exchange
NBX (Network Branch Exchange)
  • 3Com
  • POSIX (Real-time Embedded UNIX)
  • Layer 2 Protocol
  • Can ride inside of IP Packets
sip session initiation protocol
SIP (Session Initiation Protocol)
  • Industry Standard
  • Allows use though 1 firewall
  • TCP and UDP ports 5060
h 323
H.323
  • Example is Microsoft Netmeeting
  • Directly Support Video
  • Doesn’t like firewalls much
iax2 inter asterisk exchange
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
cellular
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)
switches
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
plexes
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
encodes
Encodes
  • Analog to Digital
  • TDM (Time-Division Multiplexing)
    • 64Kbps x 24 Channels = 1.536 Mbps
  • PCM (Pulse Code Modulation)
    • 8-bits x 8000 Hz
codec coder decoder
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
modulation
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
asterisk
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
3com nbx
3com NBX
  • Hopefully I can demo the Phone
  • NBX, Layer 2
  • Can ride in IP
other definitions
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
other definitions39
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)
references helpful web links
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/