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. If the error was corrected in a later version or reprint the date of the correction will be displayed in the column titled "Date Corrected".

The following errata were submitted by our customers and approved as valid errors by the author or editor.

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

Version Location Description Submitted By Date submitted Date corrected
Printed
Page 26
Figure 2-5.

The IP Phone addresses are wrong. Should end 103 and 104, instead of 03 and 04.

 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.

Note from the Author or Editor:
This is not necessarily a mistake more than an obsolescence issue. At the time the book was published, CVS was still employed by Digium. It's fine to use the updated commands. I tested them and they work. Please remove the parenthetical remarks from this reader's commands before using them, of course.

Anonymous  Jul 30, 2008  Dec 01, 2008
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

Note from the Author or Editor:
In the examples given at this point in the book, the init scripts are not employed and the sample files are not referenced. The configure commands mentioned are indeed necessary, so the script provided by the reader is a worthwhile change to resolve this error.

 Anonymous  Jul 30, 2008  Dec 01, 2008
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

Note from the Author or Editor:
Zapata.conf may or may not exist depending on a couple of factors, including the manner in which the Zaptel drivers were built. It is unclear to me whether the build instructions contained in the book will yield the correct file or not, so I will assume that this reader followed them to a T and ran into the missing file.

Anonymous  Jul 30, 2008  Dec 01, 2008
Printed
Page 86
last paragraph

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

 Anonymous  Jul 30, 2008  Dec 01, 2008
Printed
Page 114
6.2.2.5, 2nd paragraph

Most of the codecs in use on VoIP networks were defined by ITU-T recommendations in
of the G variety...

should probably be

Most of the codecs in use on VoIP networks were defined by ITU-T recommendations in
the G variety...

 Anonymous   
Printed
Page 115
2nd paragraph

Book says that uLaw and ALaw are two variants of the G.711 codec, one using a
logarithmic digitizing scale to garde amplitude levels, while the other uses a
linear one. This is not true, uLaw and ALaw both use a logarithmic scale.

 Anonymous   
Printed
Page 121
3rd paragraph

You refer to RFC 1889, which was already quite outdated when this book was printed.
The current specification of the RTP/RTCP protocol can be found in RFC 3550.
Furthermore in your short summary of RTP's functionality, you have completely
neglected two of its most important features: timestamping and sequence numbering.

 Anonymous   
Printed
Page 144
Third line

"export LD_LIBRARY_PAT" NOW READS "export LD_LIBRARY_PATH"

 Anonymous    Mar 01, 2006
Printed
Page 152
Figurec7-9

Between "A" and "B" there is now "Invite 5105@oreilly.com". It should be 5150 (not 5105).

 Anonymous   
Printed
Page 154
Figure 7-11.

"madelyn@orelly.com" should be "madelyn@oreilly.com"

 Anonymous   
Printed
Page 155
4th paragraph

"HanSolo at 10.1.1.203" NOW READS "HanSolo at 10.1.1.103"

 Anonymous    Mar 01, 2006
Printed
Page 162
Figure 7-13

"INVITE to jake@oreilly.com" should be "INVITE to 3002@oreilly.com"

 Anonymous   
Printed
Page 193
1st paragraph

On page 193, you wrote: "Research has established that round-trip latency less than
150 ms is not immediately noticeable, but latency higher than 150 ms is discouraged,
and latency higher than 300 ms is considered unacceptable."
Actually, the majority of other literature sources (including ITU-T recommendation
G.114, which is also referenced on page 193 in your book) uses these numbers not as
boundaries for the round-trip latency, but for the one-way latency.

 Anonymous   
Printed
Page 201
last item on page,the code snippet

iptables -A PREROUTING -p udp -D 0.0.0.0/0.0.0.0 --dport 5004 -j DSCP --set-dscp-class EF

NOW READS:
iptables -A PREROUTING -p udp -d 0.0.0.0/0.0.0.0 --dport 5004 -j DSCP --set-dscp-class EF

 Anonymous    Mar 01, 2006
Printed
Page 331
Terminology Recap box

Under PCM, "Pulse ccde modulation" NOW READS "Pulse code modulation".

 Anonymous    Mar 01, 2006
Printed
Page 354
Tip in middle of page

"Even though Asterisk no longer supports MySQL for CDR, because of license conflicts, AMP still
uses MySQL to store its dial-plan"

NOW READS:
"AMP uses MySQL to store its dial-plan configuration."

 Anonymous    Sep 01, 2005
Printed
Page 382
third paragraph

"principle" NOW READS "principal."

also, on the 4th line;
Susbcribing

NOW READS:
Subscribing

 Anonymous    Mar 01, 2006