Comp 346/488: Intro to Telecommunications

Tuesdays and Thursdays, 6:00-9:15, Lewis Towers 410

Class 3
AICN readings:
    An Overview of Networks
Optional reading (Stallings 7th -- 9th editions)
10.1, 10.2, 10.3
Chapter 1: 1.3, 1.4
Chapter 2, 2.1-2.6, especially 2.3 on TCP/IP

Homework 1 is now on Sakai. It is due Friday, July 17.

Network Signal Info

This is an app (there are both free and pro versions) available only for Android. The developer site is

It provides information on your cellular and LTE network: signal strength, cell (station/system/network), MNC/MCC, etc. Right now, for example, it shows my cell as
    station ID 34497
    system ID  4384
    network id   122
My MCC (Mobile Country Code) is 311, and my MNC (Mobile Network Code) is 580. We can look these up at to find this is US Cellular.


The next blog post by Whisper Systems, on Client-Side Audio Quality, goes on to say

All VoIP solutions contend with packet switched networks that were not designed to transmit real-time media streams. Packet latency and packet loss are the principal manifestations of this reality, and the jitter buffer is their canonical solution.

They then describe an adaptive-jitter-buffer algorithm, where the buffer can change size. That's a bit of a trick, as that means slowing down or speeding up the audio. In order to do this at all, one must know that sometimes voice can be stretched (eg by pausing), or shortened. For voice, the resultant distortion is generally acceptable; for music, it is likely not.


Sound as data: digitized_sound.html
    beginning with Fourier Analysis visualization

    Start in on modulation

Telecom terminology: pots.html

Asterisk: configuring a phone
    Ekiga demo with headset
    PBX Terminology: asterisk_basics.html