On Sun, Nov 20, 2005 at 11:31:51PM +0300, Maxim Vexler wrote:
> Hello,
> I wish to use asterisk in my home, the poor man's way.
> Can asterisk be used in a home environment with plain analog modem ?I wish
> use the modem to listen the line, basically simulating theregular phone
> device.In the old days you could receive caller id on the signal that wassent
> by bezeq on the first ring tone... can I do the same withasterisk?
> Plus I'm a bit confused with all this FXO / FXS telephone hardware andwould
> thank any one willing to clarify this for me in a line or 2. Whydo I even
> need this FXO / FXS telephone equipment if I can simply plugthe VoIP phone
> into the LAN socket and have it receive the voltagefrom the switch ?
> I did goolgled, and alos done my reading on voip-info.org, but stillcouldn't
> find a concise answer to my questions.
> Thank you for reading.
There are basicly 4 ways that asterisk can talk to a telephone or telephone
line.
1. FXO (stands for foreign exchange OFFICE), this is a line from a
telephone switch (BEZEQ) to your computer. The best ones are
standard FXO line cards.
An Intel "smartmodem" can be used as an FXO card. It's advantage
is it's cheap (under 100 NIS), it's disadvantage is that it
hits your ssystem with 8,000 interupts a second. Theoreticaly
you could put one in each of your PCI slots, in practice, no
system could handle that many.
2. FXS (foreign exchange SUBSCRIBER), These cards go to analog
(aka POTS) phones.
3. Ethernet. This is for "smart" phones (phones with ethernet ports
that use a supported protocol, usually SIP) or a "soft" phone,
a program running on a computer.
It can also connect to the internet for VoIP (voice over IP
services) for both incoming and outgoing calls.
4. Hi speed serial ports. These can be slow such as ISDN (2 64kbps
channels and a 16kbps control channel) or fast such as a T1 voice
or ISDN PRI (known in Israel as a PRA). which combines many lines.
There are many pitfalls you should be aware of. Asterisk can be memory
and CPU expensive and need frequent reboots. For a single line using a
real FXO card, a single 4 extension FXS card for your old phones and
a smart/soft phone or two a relatively small system (1gHz CPU, 512m RAM,
40 gig disk will do nicely and probably need to be rebooted once a week
or so.
A smaller system such as a 500mHz CPU, 256m RAM and 10 gig disk will do
ok, but it may need more frequent reboots. If you spend some time tailoring
your Linux system it runs on and recompile from source with the small
system option, a 300mHz cpu, 128m RAM and 6g HD will do.
Using the Intel chipset smart modems adds a lot of overhead, so what you
save in not bying FXO/FXS cards can be eaten up quickly if you have to
buy a computer, even a used one.
You need to be careful in buying your equipment, USB and Ethernet
devices sold for Skype do not have linux support and can't be used.
I purchased such a device from an Israeli manufacturer and found out later
that it was not made, designed or supported by them.
They just imported it, put their name on the docs and drivers and filed
the paperwork to be allowed to import it. The same unit is sold by at
least 20 other vendors around the world as their own, with the same
drivers having their name on it.
There are are least two importers of FXO/FXS cards in Israel, look at the
archives of this list for their names.
As for the future of Asterisk, I make the following prediction:
Asterisk will be the phone switch of choice for many of the small startups
that appear in the coming "high-tech" bubble. If you specialize in installing
and maintaing asterisk systems in the 5-10 user range, you will find an
"emerging" market and do well.
Geoff.
--
Geoffrey S. Mendelson, Jerusalem, Israel [EMAIL PROTECTED] N3OWJ/4X1GM
IL Voice: (07)-7424-1667 IL Fax: 972-2-648-1443 U.S. Voice: 1-215-821-1838
You should have boycotted Google while you could, now Google supported
BPL is in action. Time is running out on worldwide radio communication.
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