1. ring down circuit
    no dialing of numbers, just physical connection
  2. Alexander Graham Bell
    inventor of ring down circuit
  3. switch ( end office switch)
    the cable from the telephone( your home) to centralized switch office whats the device
  4. PSTN
    the telephone system of an enterprise company
  5. POTS – Plain Old Telephone System / Service
    Term for traditional single residental line
  6. line noise
    the static onto the voice network by electrical appliances
  7. accumulated noice
    process of going through several amplifers with one voice signal
  8. repeater ( digital amplifer)
    not only clean it but amplify the signal to its original condition with 1s and 0's
  9. 7 times
    max number you cna clean up a signal
  10. Pulse Code Modulation (PCM)
    most common method of encoding an analog voice signal into a digital stream of 1s and 0s.
  11. voice frequency filter
    what filters out anything greater then 4000 hz
  12. Nyquist theorem
    if you sample at twice the highest frequency on a voice line, you achieve good-quality voice transmission. 8000 times per sec
  13. voice frequency filter
    filter out anything greater than 4000 Hz
  14. quantization
    wave is then coverted into a discrete digital form
  15. 8 bits
    PCM uses how many bits for code and logaritm compression
  16. 64,000bps(bits per second) or 64 kbps
    telephone structure is based what speed
  17. µ-law
    : the standard used in North America and Japan
  18. u-law
    the standard in europe
  19. u-law
    what contry is responsibe for long distance calls from u-law to a-law
  20. Local loop (or Class 5 switch or endoffice switch)
    connects home telephone to the central office switch
  21. tandem switches (class 4 switches)
    end office switches interconnect through trunks to
  22. Trunk
    communication path between several central office switches
  23. class 5 switch
    switch services include basic dial-tone, calling features, and additional digital and data services to subscribers using the local loop.
  24. user to network signaling
    How an end user communicates with the PSTN.
  25. Network-to-network signaling
    How the switches in the PSTN intercommunicate
  26. analog,** Integrated Services Digital Network (ISDN) **or T1
    when using twisted coper the user connects through
  27. Dual Tone Multi-Frequency (DTMF)
    The most common signaling method for user-to-network analog communication
  28. DTMF
    is known as in-band signaling because the tones are carried through the voice path.
  29. ISND
    • uses out of band signaling
    • the signal is transported on a channel separated from the voice (D-Channel)
  30. is faster
    glare reduced
    set up the line faster
    benefits of out of band signaling
  31. glare
    when two people are on the same circuit at the same time. (both dialing at the same time)
  32. bearer (B channel)
    the channel on which voice data and fax is carried on
  33. data or control channel (D channel)
    the channel on which the signal is carried
  34. Basic Rate Interface (BRI)
    2 64 kbps B channels and one 16kbps D channel
  35. Primary Rate Interface (PRI)
    23 64 kbps B channels and one 64kbps D channellarge enterprise
  36. network to network
    network to network
  37. T1/E1, and SONET
    Network to network communication is carried on
  38. E1
    2.048Mbps in europe
  39. T1 carrier over twisted pair
    is a 1.544-Mbps digital transmission link normally used in North America and Japan
  40. T4 handles
    168 T1 circuits or 4032 4-kbps connections and is 274.176 Mbps
  41. circuit based
    what type of system is a wast of bandwidth
  42. 50%
    percentage of a call that is silent overhead
  43. Multi-Frequency (MF)
    Robbed Bit Signaling (RBS)
    what are the 2 in-band signaling methods
  44. SS7
    what network to network also use out of band signaling
  45. out of band signaling
    interconnect to the Intelligent Network (IN)
    Makes the PSTN to offer CLASS (custon local Area signaling services) services
    why is SS7 beneficial
  46. set up telephone calls between switches
    open standard
    what are the benefits of SS7
  47. Local Numbe Portability (LNP)
    Reduced post-dialing delay- faster
    Increased call completion- singal pckets that contain all the information are fast then tones.
    Additional services (ANI, call blocking, etc.)
    Services can be transparent across multiple vendors’ switching equipment
    Connection to the IN enables the PSTN to offer Custom Local Area Signaling Services (CLASS) services such as
  48. regular busy signal
    the end user is busy ( person is on the line but wont answer)
  49. all the circuits are full. ( when all the lines are full and it cant dedicate a 64bit channel)
    fast busy
  50. custom calling
    rely on the end office switch not the entire pstn to carry into from circuit switch to circuit switch
  51. CLASS features
    require ss7 connecticity to carry features to from end to end PSTN
  52. North American Numbering Plan (NANP)
    • 11 digit plan
    • 1-NPA-NXX(central office code)-XXXX
    • N= 2-9
    • x=0-9
    • ◦3 parts NPA-NXX-XXXX (traditional)
  53. statation number
    the last 4 digets (extension)
  54. overlay
    when you have to dial 1+ 10 digets because of diff area codes
  55. Local Exchange Carrier (LEC)
    keeps track of long distance providers in a static table on the CO switch.( gives us the dial tone)
  56. North AmericanNumbering Plan Association (NANPA)
    who gives the long distance code
  57. IXC – Inter-Exchange Carrier
    is routed to the proper long distance network carrier
  58. ITU-T International Numbering Plan
    • Recommendation E.164 specifies the following be used to route a call
    • Country Code (CC)- 1,2 or 3 digits. First digit defines world numbering zones
    • National DestinationCode (NDC)- Less than or equal
    • to 15 digits
    • Subscriber Number (SN)- Less than or equal
    • to 15 digits
  59. Data has overtaken voice as the primary traffic on many networks built for voice.
    The PSTN cannot create and deploy features quickly enough.
    Data/Voice/Video (D/V/V) cannot converge on the PSTN as currently built.
    The architecture built for voice is not flexible enough to carry data.
    Circuit-switched calls require a permanent 64-kbps dedicated circuit between the two telephones.
    Key *voice is made for reliabilty and over lost conversation*
    Drawbacks to the PSTN
  60. the layers are open standard
    security is good
    why use circuit switched
  61. payload
    ip simpley transports data end to end with no real interest in
  62. Real-time Transport Protocol (RTP)
    • Is utilized in addition to a User Datagram Protocol (UDP)/IP header to provide timestamping.
    • Currently the cornerstone for carrying real-time traffic across IP networks.
  63. RTP
    • runs atop UDP and IP and is commonly noted as RTP/UDP/ IP
    • one-way delay of no more than 150 ms.
  64. jitter and delay
    UDP check for
  65. delay and jitter
    rtp is sensity to
  66. H.323
    ITU-T recomendation for Voip call ( how multimedia traffic is carried over packet networks)
  67. VoIP Call-Control Protocols
    As of this writing, the main VoIP call-control protocols are SIP, H.323, MGCP, and H.248/MEGACO
  68. SIP
    a media-based protocol that will enable end devices (endpoints or gateways) to be more intelligent
  69. Open Service Application Layer
    Thousands of new enhanced applications can be specifically developed for packet infrastructures (great for call centers)
  70. Reliability
    Network stability
    Guaranteed bandwidth per call, call quality
    More feature-rich PBX environment
    No “viruses” or other user-induced problems
    Reasons to choose traditional PSTN
  71. cheaper in long run
    maintance is better
    more application
    reduce load and biandwidth
    but security not as good
    why choose voip
  72. a fax machine
    what are ATA's for
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