To create a little VoIP system you need the following hardware:
- PC 386
card, full duplex capable
- a network
card or connection to internet or other kind of interface to allow communication
between 2 PCs
has to be present twice to simulate a standard communication.
tool above are the minimal requirement for a VoIP connection: next we'll
see that we should (and in Internet we must) use more hardware to do the
same in a real situation.
card has be full duplex unless we couldn't hear anything while speaking!
additional you can use hardware cards (see next) able to manage data stream
in a compressed format (see Par 4.3).
Hardware accelerating cards
We can use special cards with hardware accelerating capability. Two of
them (and also the only ones directly managed by the Linux kernel at this
moment) are the
PhoneJack is a sound card that can use standard algorithms to compress
audio stream like G723.1 (section 4.3) down to 4.1 Kbps rate.
It can be connected directly to a phone (POTS port) or a couple mic-speaker.
It has a ISA or PCI connector bus.
Quicknet LineJack works like PhoneJack with some addition features (see
VoiceTronix V4PCI is a PCI card pretty like Quicknet LineJack but with
4 phone ports
VoiceTronix VPB4 is a ISA card equivalent to V4PCI.
VoiceTronix VPB8L is a logging card with 8 ports.
For more info see Quicknet web site and VoiceTronix web site
Hardware gateway cards
Quicknet LineJack and VoiceTronix cards can be connected to a PSTN line
allowing VoIP gateway feature.
you'll need a software to manage it (see after).
We can choose what O.S. to use:
we have Microsoft Netmeeting, Internet Phone, DialPad or others or Internet
Switchboard (from Quicknet web site) for Quicknet cards.
Warning!!: Latest Quicknet cards using Swithboard (older version too)
NEED to be connected to Internet to get working for managing Microtelco
account (not free of charge), so if you plan to remain isolated from Internet
you need to install OpenH323 software.
For VoiceTronix cards you can find software at VoiceTronix web site
U nder Linux we have free software GnomeMeeting, a clone of Microsoft
Netmeeting, while in console mode we use (also free software) applications
from OpenH323 web site: simph323 or ohphone that can also work with Quicknet
Attention: all Openh323 source code has to be compiled in a user directory
(if not it is necessary to change some environment variable). You are
warned that compiling time could be very high and you could need a lot
of RAM to make it in a decent time.
To manage gateway feature (join TCP/IP VoIP to PSTN lines) you need some
kind of software like this:
SwitchBoard (only when connected to Internet) for Windows systems also
acting as a h323 terminal;
for Linux and Windows systems you download from OpenH323.
You can choose as gatekeeper:
you can download from opengatekeeper web site for Linux and Win9x.
Gatekeeper (GK) from here.
In addition I report some useful software h323 compliant:
able to solve problems behind a NAT firewall. It simply allows users
(external or internal) calling from a web page (which is reachable from
even external and internal users): when web application understands
the remote host is ready, it calls (h323) the source telling it all
is ok and communication can be established. Phonepatch is a proprietary
software (with also a demo version for no more than 3 minutes long conversations)
you download from here.
of this content on VoIP was taken from VoIP Howto, written by Roberto
Arcomano firstname.lastname@example.org on v1.7, August 7, 2002. The most up to
date version of this information can be found at: http://www.fatamorgana.com/bertolinux
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