Errata

Switching to VoIP

Errata for Switching to VoIP

Submit your own errata for this product.

The errata list is a list of errors and their corrections that were found after the product was released.

The following errata were submitted by our customers and have not yet been approved or disproved by the author or editor. They solely represent the opinion of the customer.

Color Key: Serious technical mistake Minor technical mistake Language or formatting error Typo Question Note Update

Version Location Description Submitted by Date submitted
Printed Page 2
Mesh Vs Switched (bottom of page)

The number of links (L) in a mesh network is = (L * (L-1))/2.

For 10 end points, this is 45 and for 100 end points this is 4950.

 Anonymous   
Printed Page 16
Thirs para from bottom

The explanation is slightly confusing. I suggest something along the lines of:

"An IP address consists of 32 binary bits, commonly represented by 4 decimal numbers separated by dots:

192.12.12.204"

The example given, 10.1.1.204, has a binary look, and it took me a little while to figure out exactly what the author meant. Also, I suggest the word "number" is used in place of figure, as figure refers to diagrams.

 Anonymous   
Printed Page 41
bottom of page

Digium uses svn (subversion) now instead of CVS for its versioning system. In light of that, the commands on page 41 should read:

# cd /usr/src
# svn checkout http://svn.digium.com/svn/zaptel/branches/1.4 zaptel (drivers for the X100P card)
# svn checkout http://svn.digium.com/svn/libpri/branches/1.4 libpri (drivers for Digium T1 cards)
# svn checkout http://svn.digium.com/svn/asterisk/branches/1.4 asterisk

Page 36 paragraph 3 perhaps should also be updated to indicate that subversion package also needs to be installed.

 Anonymous   
Printed Page 42
middle of the page

Commands for compiling asterisk are incomplete. Here is what I found works (see the notes for lines that were added):

# cd zaptel
# ./configure ##needed before following make commands
# make clean ; make install
# make config ##creates init.d scripts
# cd ../libpri
# make clean ; make install
# cd ../asterisk
# ./configure ##needed before following make commands
# make clean ; make install
# make samples
# make config ##creates init.d scripts

 Anonymous   
Printed Page 43
middle of the page

It might be helpful to include some troubleshooting tips for the X100P. Apparently this card is very sensitive to IRQ conflicts. I couldn't get mine to work till I moved it to a different machine. Perhaps you could provide a link to the following document installation guide which includes troubleshooting instructions:

http://www.x100p.com/support/doc/novavox-x100p-se-installation-guide.pdf

The X100P cards can also be purchased new from this site.

 Anonymous   
Printed Page 46
Top, first paragraph

To kill the asterisk process you would type:
#kill -9 424

not

#kill -9 425

 Amrom Morgenstern  Jan 17, 2010 
Printed Page 48
full page

Not sure what is wrong here, but I was unable to "secure" asterisk using these instructions.

 Anonymous   
Printed Page 48
full page

Not sure what is wrong here, but I was unable to "secure" asterisk using these instructions.

 Anonymous  Jul 30, 2008 
Printed Page 50
2nd paragraph

Book says, "you should get a 404 message on the phone's display". I did not, rather I got the automated attendant.

 Anonymous   
Printed Page 60
Top figure 4-1

The figure does very little to show the different state or federal agencies. It is simply a diagram of different carrier types. the reference to this figure on the bottom of page 59 is therefore unclear.

 Amrom Morgenstern  Jan 17, 2010 
Printed Page 62
Third para from top

"At the edge of the PSTN are large, mainframe-like switches CALLED exchanges"

 Anonymous   
Printed Page 72
second to last paragraph

/etc/asterisk/zapata.conf file does not exist initially. I had to create it using the following syntax (note the [channels]):

[channels]
context=default
signalling=fxs_ks
usecallerid=yes
echocancel=yes
callgroup=1
pickupgroup=1
immediate=no
callerid="* X100P POTS"<(314) 514-8528>
channel=>1

 Anonymous   
Printed Page 86
last paragraph

/etc/extensions.conf should be /etc/asterisk/extensions.conf

 Anonymous   
Printed Page 112
6.2.1, 3rd para

"DAC includes of quantizing or digital "sampling" of sounds,"
^^
Missing word?

{111/112} Third para from top;
The section called "Sampling and Digitizing"

This section mostly deals with ADC not DAC, yet DAC is used exclusively. There are one or two language errors as well. For instance, the last para in the section makes it clear that ADC is being discussed, and should read:

"ADC includes quantizing or digital "sampling" of sounds, filtering for bandwidth?"

I suggest the whole section be rewritten, starting with:

"Analog-to-digital conversion (ADC) and digital-to-analog conversion (DAC) are the processes that convert?"

In some places the term ADC/DAC should be used when both processes are being referred to.

 Anonymous   
Printed Page 117
First para

"A 30ms sound frame takes a third longer to encode than a 20 ms one?"

No it doesn't. It takes 50% longer.

 Anonymous   
Printed Page 119
Table at top

The "Voice bits per packet" for G.729A and GSM may be incorrect. For G.729A it should be 80 bits, and for GSM 260 bits.

 Anonymous   
Printed Page 195
2nd para

"Chances are, if the echo occurs less than 150 ms from the time you actually said the words, then you won't notice it".

Wrong. I think the figure is only 15 ms.

 Anonymous