Answers: Do you really know VoIP?

Here are the answers to the Do You Know VoIP Quiz on Check and see how much you really know about the latest in IP telephony. If you haven't taken the quiz yet, go check it out and come back to compare answers!

Do you know how VoIP works? We shall see! If your scores are not as high as you you'd like, read's How does VoIP work?: A technical guide to functional VoIP and make the VoIP grade.


  1. 8




  2. One party or the other goes "on-hook."



  3. header and payload



  4. destination address/es and originator's address



  5. It does not carry any address information at all.



  6. error detection



  7. With DRMF tones or with an IAM in CCITT Signaling System No. 7



  8. Mouth-to-ear delay, impact of errored frames, lost packets or frames, variation of packet arrival time, prioritizing VoIP traffic over other internet traffic, talker echo, distortion -- voice quality, voice coding algorithm for standardization, sufficient bit rate capacity, optimized standard packet payload size, packet overhead (efficiency), silence suppression)



  9. Network management, authentication, voice prompts, PSTN interface, QoS records, H.323 functions



  10. copper pair, ADSL, CATV cable, fiber (SONET/SD), radio, PDH PCM formats



  11. POTS voice, data octets, DTMF tones



  12. 80 or 160



  13. 100 ms



  14. 400 ms



  15. Propagation time



  16. To detect patterns in voice transmission to eventually save on bit rate capacity use



  17. A buffer may be found in packet routers where at least one frame or packet must be stored. Thus buffer delay would be a function of the number of routers in tandem.



  18. Speed up the bit rate.



  19. 10%



  20. a) disregard it
    b) use a PLC procedure to camouflage the gap



  21. Carry out a signaling function



  22. SIP, H.323, MGCP and Megaco H.248



  23. How to prioritize VoIP packets versus other data packets



  24. RTP carries out media content function whereas RTCP works with signaling functions of status and control.



  25. User agents



  26. Redirect and proxy



  27. Call agents



  28. A gateway controller and a gateway



  29. Terminations and contexts



  30. 2



  31. By terminationID.



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This was first published in June 2006

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