sundance-communications.com/forum Forums VOIP Phones & IP PBX VoIP & Cloud Phones, Hosted PBX, General IP Phones Resources for those Interested in Asterisk

If you are interested or just curious in asterisk you can use the following links to tinker with it.

Asterisk: The Future of Telephony
This book is published by O'Reilly and is available from Borders and Barnes & Nobles. The above link is to the free online publication of the Book. This book is a required must-read for anyone starting with asterisk. The current version is somewhat dated and they are in the process of releasing a new edition. This book will apply through Asterisk v.1.2.

VoIP-Info
Once you have read through the above book, and are ready for real-world examples and recipes for disaster and enlightenment, this site will be it. It contains a vast array of user-contributed programming examples, command definitions, and other misc topics. It is also a good spring-board to a wealth of information on other sites.

Digium: Creators of Asterisk
This is where Asterisk can be freely downloaded and all of the components it needs to run. For POTS you will need Asterisk, Zaptel, Asterisk-Sounds, and Asterisk-Addons. If you are going to experiment with PRI T1's, then you will need LIB-PRI as well. I usually download all 5 and install just as good measure. What's 2-3 megs of wasted hard-drive space

A simple recipe for an R&D Test Bed system would be as follows:
-Pentium MMX 200Mhz or Better (A 1gig P4 will handle 2-T1's with ease)
-Atleast 128-megs of ram
-8-Gig's of Hard-Drive or more
-an X100p card available on E-Bay or www.x100p.com (They are typically $10-30 depending on where you buy one)
Your favorite Linux distribution (I like Slack )

This test-bed will let you tinker and play with asterisk for under $200 (at the most). This will let you install, understand, and conceptualize your own dial-plans. One gotcha that this system will have is it will max out around 4-5 lines and the X100p style of cards are horrible, but cheap. Expect to have Gain and Echo issues using X100p style cards. If you want to try a quality interface card for POTS I would recommend Sangoma A200. It comes with a free software echocan for up to 6 channels, or is available with a hardware echocan. T1 Interfaces are available from Digium and Sangoma in multiple-interfaces up to 8-T1's and with or without echocan. Sangoma is also in the works on finalizing a T3 interface. If you plan to experiment solely with SIP/VoIP then just get an X100p as it is used internally by asterisk as a timing source for some functions.

If you want a SIP phone to experiment with I would recommend picking up a grandstream. Again, they are cheap phones and prove it. After you understand the basics with this phone you would be best advised to never install grandstreams for production use and to learn how to install and provision Polycom or Snom phones. Polycom is regarded as the standard by which other SIP phones are measured. Cisco phones fall short of the average Polycom, unless you count good-looks. Expect to browse through over 2000-settings when provisioning these phones. BTW, Shoretel has polycom produce it's phones and rebrand them for their systems.

I do not recommend SIP-PSTN Gateways as they tend to add undue complexity to the system/dialplan and do not allow you to maintain good control over the call. Most of them are also sub-par as far as quality goes.

Feel free to ask me any other questions you may have regarding asterisk. In the spirit of OpenSource questions are encouraged and expected

Thanks for the info Kumba, you keep this up and you may convert some of us to that dreaded voip :shhh:

I'll have you know that Alexander Grahm Bell is turning over in his grave as we speak.

How long have been you tinkering with * ?

About 2 years. Most of the installations i've done are simple 4x10 with paging/voicemail/queues/etc. I've done one 20-seat call center with a software suite called ViciDial doing outbound predictive dialing. On a different install Asterisk was coupled with a program called ZoneMinder (CCTV) and was doing the PBX part plus allowing the system to call a pre-determined call list and tell people that it had detected an intruder and play dogs and police sirens over the PA while turn the shop lights on.

You can do some fairly interesting things with it once you get past the learning curve. The hardest part for me to learn was how the Dialplan scripting worked. Once you get over the basic scripting syntax and flow, it's pretty limitless in how it can be used.

But like others have mentioned in previous posts on this board, it's not a proceduralized install. In other words, it's more of a blank canvas then a paint-by-number.

Asterisk is like a bucket full of Legos- if you know what you're doing it's easy to make something cool, If you don't its easy to make a mess.

Also just wanted to add one thing for anybody planning on building this- X100 type cards suck.
They are fine if you want to play around and learn asterisk, a great way to get started for $20. But don't ever use an X100 in a business environment, or in a situation where it failing will cost someone money.
X100 cards can (but don't always) have a number of odd issues, including (but not limited to)-
random hangups
incorrect hangup detection (card doesn't know when to hang up)
callerID problems
incorrect / unworkable DTMF detection
heavy, unsolvable echo problems
Furthermore, the X100's have a fixed impedence as i recall which makes them unsuitable for use in many countries.

They're fun to play with though but if you are doing something real don't cheap out, buy quality parts from Digium or Sangoma or another reputable Asterisk supplier.

X100's only real use in a production environment are as a cheap timer source. To actually use one for lines is a very very bad idea unless it's your test-bed beater machine. Chances are you will have a real need for atleast 1 POTS line so you will never need to use an X100 anyways. Only time I can remember someone needing an X100 in production was when they were using the system as a large conferencing engine and the X100 was just a 1Khz timer. Nothing else.

I prefer sangoma but that's like comparing red to blue. Digium's hardware has improved lately and they are starting to push some good stuff.

And these days you don't even really need a timer anymore- ztdummy works much better than in the old days. As of 2.6.somethingorother it gets its timing from the kernel rather than the USB bus (gah what an ugly hack that was). I've found ztdummy to be quite reliable...

ZTDummy is still not reliable under moderate to heavy loads. It will still slip. For light loads it will work. I would not use Asterisk without a dedicated timer source. If the price of an X100p card is too much then you have other issues anyways.

Sangoma is making a usb device (dont know when it will be released) to act as a strict 1Khz timer. This should alleviate the problems with ZTDummy under high load.

Using ZTDummy with a 1K realtime clock will be about as stable as it will get.