[Asterisk-Users] Newbie General questions

[Benjamin on Asterisk Mailing Lists]

On Fri, 22 Oct 2004 10:46:22 +0200, Philippe Dhont   (Sea-ro)
<philippe.dhont at searo.be> wrote:
> 1) if i setup asterisk, do i need additional hardware if other computers
> via internet want to talk to me ?

if all you want is IP based telephony only, then all you need is
ethernet, LAN wiring, hub, router, ADSL or Cable modem or FTTH media
converter, in other words stuff you probably already have.

> 2) How do you call somewhone else ? If someone is at the other side of
> the world and he has a softphone on his computer installed, does he just
> has to enter the number (IP) of my server ?

in theory yes, but in practise there are obstacles you have to
overcome with various workarounds. The most popular such obstacle is
NAT.

the easiest way to get connected to other IP phones is to join a free
directory service, like for example Free World Dialup aka FWD at
http://www.freeworddialup.com. You can sign up online, get an FWD
number and anybody who is also signed up with FWD or who is signed up
with a service that has peering with FWD will be able to call you via
your FWD number.

> 3) What softphones are good ?

none, whatsoever. softphones are a compromise. softphones are bait.
they are ok for testing before you are ready to commit yourself to
buying real IP phones and they are handy in travel situations. other
than that one should stay away from softphones.

> Any links to opensource/free softphones for linux and windows ?

search the Wiki at http://www.voip-info.org

> 4) is someone calls me from somewhere, let's say a hotel and he is after
> a firewall and got on the net via a router so he is in a private ip
> domain, will the communcation work or is it a client-client communcation
> one the connection is made ?

Depends on the protocol you use.

If you use one of the
we-are-telephone-people-how-are-we-supposed-to-know-how-tcpip-is-meant-to-work
VoIP protocols like H.323 and SIP etc, then you will need one or more
hacks to get things working behind NAT. All of those hacks have
serious drawbacks, most of them compromise network security.

If you use a designed-by-people-who-actually-understand-tcpip VoIP
protocol, like IAX, then all you need is have your client register
periodically with your server and things will work like magic.

the following is your recommended check list ...

- if you have to use SIP, don't use NAT
- if you have to use NAT, use IAX
- if you have to use both SIP and NAT, use VPN to build a tunnel

anything outside of those recommendations is the equivalent of using
duct tape to build a house.

> 5) If my phone server has an ip address that changes every day, is there
> a solution for this ?

http://www.dyndns.org

> Can i install such a free ip-domain-linker and let my softphone connect
> to that name instead of directly the ip address ?

yes, but you may experience short outages from time to time depending
on how fast the dynamic DNS service you are using can keep up with
your address changes.

rgds
benjk

-- 
Sunrise Telephone Systems, 9F Shibuya Daikyo Bldg., 1-13-5 Shibuya,
Tokyo, Japan.

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