Building an Embedded Asterisk PBX Part 3

The IP04 is a Four Port Embedded IP PBX that runs Asterisk. The hardware design is 100% open. I just built the first IP04 prototype (really built, as in soldered), and would like to tell you about it.

This post talks about the IP04 hardware, the bring up, an explosion (!).

Hot Solder

You know surface mount soldering is fun. Really fun. It’s a nice break from the thinking-oriented work I normally do, like DSP, programming, and fighting zillion level deep makefiles that are needed for embedded systems. There is just something about making stuff with your hands. It even looks nice at the end, you can hold it and show it off to your wife and kids. Of course they don’t actually care but you can still show them!

After building a BlackfinOne, I found the IP04 quite easy to put together. I would recommend it to anyone who wants a first surface mount or embedded Linux hardware project. It’s kind of amazing, but with a days work you can build (as in solder) your very own embedded Linux system.

Flux, a stereo microscope, and a good quality PCB really help make surface mount soldering a pleasure. Tip: I check each pin of the chips after soldering by attempting to wiggle it with a sewing needle.

So I had a very enjoyable day soldering the IP04 prototype under the stereo microscope. After loading the surface mount components I gave the board a “bath” to remove the flux residue. I actually put the PCB in a bowl of hot water and used a small brush to scrub that nasty conductive flux off (conductive flux residue caused me a lot of problems when building a BlackfinOne). After washing I soaked up excess water with paper towels then put it under a hot lamp to dry quickly.

Open Hardware Hacking

Curiously, hardware hacking is getting cheaper and easier. For example the tools for surface mount work are reasonably cheap (a soldering iron and stereo microscope), there is plenty of free CAD software, low cost PCB fabrication, and web based components stores like Digikey.

With the growth of open hardware projects, they are plenty of cool designs and people on line who can help you if you get stuck.

How the IP04 Works

Here is a block diagram of the IP04 hardware architecture:

You may also like to take a look at the IP04 schematic.

When power is applied, the Blackfin boot ROM starts reading from the little 256k SPI flash chip. The program it loads is called u-boot, a powerful boot loader that has been ported to the Blackfin by the Analog Devices Blackfin team. U-boot has a command line interface that lets you load other programs from flash or via Ethernet. In normal operation it automatically loads and executes the uClinux kernel.

NAND flash is used as the main storage for the IP04. NAND flash has the advantage of high density and low cost. It’s the same stuff that is used in your MP3 player, so prices have plummeted over recent years. However the Blackfin boot ROM can’t read the NAND flash directly, which is why we need the SPI flash chip and U-boot to support the start up process. Compared to many embedded linux systems, the IP04 requires a lot of flash storage (around 16M minimum) to store the Asterisk executable and audio prompts.

When the kernel boots it runs out of SDRAM, and the NAND flash is mapped to the root filesystem. We also use a portion of the SDRAM for temporary files, e.g. /tmp.

If you would like to learn more about IP-PBX design see the Resources section of the Free Telephony Project website.

An Explosion!

So it was time for the moment of truth. After a run of successful hardware projects I was feeling pretty confident, which of course angered the Gods of open hardware. I applied 12V and started poking about with my multimeter. About 3 seconds later – BANG!. A small mushroom cloud rises a few inches off the board and gently drifts across the bench. A nasty smell fills the air, along with a string of expletives that bring the family running.

“Dad, can you do it again?”, my 8 year old son asks! He was ejected from my office shortly afterwards.

I sniffed a few areas of the board to track down the general problem area. A peek through the microscope showed a capacitor had blown it’s guts out, the white fuzzy stuff on the left of this picture:

The problem was two capacitors had their labels swapped on the PCB silkscreen. This meant I had loaded a capacitor with a 6V rating where there should have been a 25V rated capacitor. When 12V was applied – the 6V rated capacitor expressed it’s displeasure!

Apart from that the remaining assembly and bring up went pretty smoothly. One mistake I made was forgetting to supply power to the Real Time Clock (RTC). This caused U-boot to stall when it started, waiting for the RTC clock to come up. Of course, when this bug appeared I had no idea if it was a hardware or software problem. So I had to hunt through various possibilities in “bug space”, for example sprinkling printfs through the U-boot code to find out where it was stalling. Unfortunately, each new load of software took 20 minutes to flash via the Igloo JTAG cable, so it was a slow process that took 2 minutes to fix once I found it.

I modified the u-boot and uClinux configuration a little from the BlackfinOne baseline due to minor differences between the two boards; for example the smaller SPI flash, one Ethernet port, and the use of NAND flash. This was fun – I learnt a lot about U-boot and the set up of NAND flash through the MTD driver. By this time I had u-boot running so I could download new images via Ethernet and test in a few seconds.

I was re-using tested building blocks from the BlackfinOne and 4fx designs so it all went smoothly. One week from initial power up uClinux was booting and Asterisk running with 4 analog ports. Rather than stressing over the little bugs and trying to race though I took my time and enjoyed the bring up process.

Finally, I lifted the handset on a telephone connected to the IP04 and there was the dial tone! Nice.

Automated Asterisk Load Testing

The Asterisk 1.4 GUI works although it isn’t stable at present on the IP04. Sometimes the GUI freezes and I can see some core dumps on the IP04 console. This could be a Blackfin specific issue, for example uClinux is more fussy about stack space than regular MMU-enabled Linux. Some more work required to sort this one out. In the mean time, vi and Asterisk conf files are OK with me!

I was keen to see how stable the new hardware was, so I used some scripts to load the PBX over a 12 hour period. Here is a block diagram of the test set up:

A simple shell script on the x86 Asterisk box:

#!/bin/sh
# lotsofcalls.sh
# David Rowe 3 April 2007
 
calls=0
rm -f /tmp/lotsofcalls.txt
touch /tmp/lotsofcalls.txt
rm -f /var/spool/asterisk/outgoing/callastfin.call
while [ 1 ]
do
    cp callastfin.call /var/spool/asterisk/outgoing
    sleep 60
    calls=`expr 1   $calls`
    echo $calls >> /tmp/lotsofcalls.txt
done

kicks off an outgoing IAX2/GSM call to the IP04 once every minute. The call makes FXS Port 4 ring, which is connected (via a phone cable) to FXO port 2. After a few rings FXO Port 2 answers and plays an IVR script for a few seconds, then hangs up. The analog phone connected to the x86 Asterisk box rings when the IP04 call connects. As long as this phone rings every minute I know the test is still running OK. I can also lift the phone when it rings, for example to make sure the audio quality is OK.

In practice I use a script to place two calls at the same time, so the total load is two IAX/GSM calls and 4 analog calls. I let this run for about 12 hours and the IP04 worked fine – 4000 calls were placed and the loadav was about 0.2 (10% of the Blackfins CPU). Much of the code is still unoptimised so this suggests we can go to much higher call loads in the future.

Anyway given that I was testing on hardware where the solder has barely cooled I was pretty happy.

Whats Next

There is still plenty to do, for example we have quite a few Astfin tickets that need working on. If anyone would like to help out please contact me or the Astfin team.

I am working with a manufacturer to put these designs into volume commercial production. The first batch of fully assembled production units will be available in mid 2007 for around $450:

In the mean time – if your feel like a cool project – you are welcome to build an IP04 yourself! Here is some more information on obtaining bare IP04 PCBs and FXS/FXO modules.

Update – Fully Assembled and Tested IP04s now Available

July 23, 2007: You can now buy your own IP04 from the Free Telephony Project on-line store. The store also stocks parts if you would like to assemble (as in solder) your own IP04. I have blogged on the Production IP04 in Part 4 of this series.

Credits

I stand on the shoulders of giants. I have tried to add just a little bit to their work. Thanks to the Astfin & BlackfinOne teams, uClinux, Analog Devices Blackfin team, and the Asterisk community. Thanks to Mike Taht for being my editor-in-chief for this post. Sorry if I forgot anybody.

Links

IP04 home page
Buy an IP04 from the Free Telephony Project on-line store
IP04 Schematic, PCB, CPLD code, Errata, and more
Building an Embedded Asterisk PBX Part 1
Building an Embedded Asterisk PBX Part 2
Building an Embedded Asterisk PBX Part 4
Building a BlackfinOne
How to make your Blackfin fly Part 1
Open Source Echo Canceller Part 1
IP04 and the Asterisk Appliance

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42 comments to Building an Embedded Asterisk PBX Part 3

  • Vu Quang Hoa

    Excellent job, David :)
    I’m taking a small survey your $10 ATA in VN, but I think I have to start another one now.
    Looking for IP04 available in stock

    Good luck

  • Any one working on ISDN BRI daughter cards for US NI-1 ISDN? When this gets into full production and ISDN card would definately be of use to me… Will be watching…If some one wants a tester to test and ISDN BRI card let me know.

  • david

    There is a project to develop BRI daughter cards (fourfin). It has reached the prototype hardware stage but has been stuck there for nearly a year now. It would be great if we could find some interested developers to pick that project up and run with it.

    Cheers,

    David

  • Frederic

    First of all, congratulations!

    When I was younger, I built quite a few Velleman kits (like the K8000 I2C computer interface board), so I know the joy of getting your freshly soldered project to life!

    Unfortunately, when I read about the $400 price tag the commercial device would have, my enthousiasm faded away mostly.
    That really is too expensive for an embedded device with only 4 fxs/fxo!

    Think about it: you can buy two Linksys SPA3000/SPA3102 interfaces (with 1 FXO and 1 FXS each) for $70 a piece.
    Add a device like the NSLU2 from Linksys to that (another $70) and flash it with Unslung firmware (or even Debian), put Asterisk on it, and for roughly half the price ($210) you have an equivalent setup, with possibly better quality more configurable FXS/FXO interfaces (those Sipura/Linksys ATAs are very nice devices that have proven to work flawlessly in many many Asterisk setups around the globe…).
    I have serveral NSLU2 devices running as a PBX in production (Asterisk 1.2 as well as 1.4 are available as IPKG packages so it’s extremely quick and easy to setup), but you have other choices as well (even integrated with a wireless router, such as the WL-500g Premium from Asus – only $80!). All of these devices have a 233Mhz CPU and 32MB RAM, so are powerful enough for a home or SOHO pbx system.

    When you are building an integrated system like yours (so no need for 3 seperate power supplies and cases!) the market price for the device should really not be higher than $200!
    Preloaded with uCLinux/Asterisk (ready to use) I would be willing to pay $250 for your system, but certainly not $400, there is simply no way we can justify that price to our customers, if another solution which costs half that price works equally as well.

  • david

    Hi Frederic,

    Thanks for your comments – you have really got me thinking! Perhaps I can’t answer all your reservations, but here are some initial thoughts:

    + The IP-04 could indeed be built and and sold for $250, at reasonable margins, and I think we will soon see this price for a 4 port IP-PBX. Sub $200 retail is certainly possible in the sort of volume SPA3000′s are made. $400 is just where I am starting – BTW my goal is more to get the technology “out there” to early adopters than build a serious business around it.

    + My dream is actually to get boxes like this out to people in developing countries for < $100 – this would require a different business model (like OLPC) but is possible from a cost of manufacture (COM) point of view.

    + The Asterisk Appliance sells for $1500 with 8 analog ports. It has the same capabilities (indeed the same architecture). Like the AA, the IP-04 could easily handle the same number of ports (12-24 I estimate on the same platform). I am guessing that Digium set this price point for good reasons.

    + I feel the IP-04 is more in the small business PBX market space, and offers excellent functionaility compared to typical PBX. Actually my gut feel is even at $600-800 it would represent good value today’s in the small office PBX market. It is a neater solution than a PCI card + PC, certainly neater than hooking several ATAs and a router together.

    + The 2FXS/2FXO configuration is simply what I am using at the moment. It can also be configured with 4 FXO and could service a small office of say 12 IP phones. Or scaled down to a smaller 1 or 2 ports for home use.

    + Frederic, a question for you. If the the configuration you suggest is superior from a price point of view, why do people (a lot of people) buy 1-4 port PCI cards like Digium TDM400s? These cost $200-$300 and require a PC to run. I can’t quite answer that – would appreciate your input.

    + For hackers connecting several ATAs and a router together might be OK, but the average end user will want a single integrated box and pay more for it. The currently pay much more than $400 for similar features.

    + BTW I am also looking at solutions to go with routers, like the $10 ATA post on this same blog. I have also played with OpenWRT and ipkg and its very cool. Disadvatage of low cost routers is limited CPU – so no (or limited) echo cancellation or codecs. The Blackfin is approximately 10x as powerful.

    Thanks again Frederic for your input. BTW I would really like to hear comments from any one else on the subject of price and comparison to ATA based solutions.

    Cheers,

    David

  • Bruce

    David,

    Fascinating project. If I may, I would suggest that one of the items to monitor during testing of your device is the audio quality of the prompts\greetings on the phone. A friend and I have been trying to build an embedded Astlinux device based on a Soekris 4801 board. All works well – but the audio quality of prompts and greetings is terrible – fuzzy, breaking up, static, dropouts. In our testing, it turns out that we aren’t able to get acceptable sound in any flavor of Asterisk, on any hardware, on any connection (voip, pots, softphone) using any codec. It just flat out sounds bad. To me, the most basic ingredient of any telephony project should be the audio quality, and I don’t buy the argument that we should put up with worse-than-cellphone quality because of the cost savings. While Asterisk is a great tool for connecting live callers together, it doesn’t play pre-recorded audio well. Just a thought – good luck on your project!

    Bruce

  • Re: cost-competitiveness

    That’s not the point for most, especially at this stage.

    This project is not at the mass-market stage, where quantities of scale drive the price of a linksys router (a very questionable PBX in my experience) down to 70 bucks. It’s just leaving the hacker stage and entering the specialty market stage. I’m sure if you are developing a mass-market device, you can go get some investment, customize this harware design in ways a linksys never could be, and bring the price down below any linksys/ATA combo out there. Open Hardware is perfect for spawning cottage industries.

    Yes ATAs are cheaper per port than ANYTHING. But virtually no one makes their PBX out of ATAs and linksys routers. ATAs get used as adjuct to PBXs for fax machines, and in the offices of hackers, not the vast SMB market.

    I have a WRT54GL (110USD) and it is anemic as hell. I can run about two SIP channels reliably under asterisk. I will never be able to do DSP stuff or change out the Processor in this thing for something faster.

    The point is that here is another industry where we can take an already significant design and run with it. With open hardware designs, if you want to build something with a little more oomph (think about running a 12 FXO and 120 SIP stations, a common config, or four FXO and 64 SIP channels), or make any other single change, your work is relatively easy. Add bluetooth, 802.11x, GSM, Brainwave_interface, whatever to meet your needs. Build an appliance that requires zero setup and ships in one box, not three from different manufacturers, to a secretary, who just plugs the FXO and power in, and it works with the cell phone numbers they entered when they ordered it. Just have a little imagination.

    Remember when the zapata telephony cards were open hardware designs, before Digium the designs and discontinued the open hardware development to make their own products? The difference there is that the zapata hardware never left the hacker stage. David can take this to the next level without a bit of help, and he’s got some interested helpers already.

  • fred flint

    What about Echo Cancellation? Since the built in Soft Echo cans in Asterisk don’t work very well I need to used Hardware or the carrier grade commercial soft echo cans available for Linux. Are they available for the blackfin?

  • david

    Hi Fred,

    I intend to use a new open source line echo canceller called Oslec that I have been developing. This is working well on x86 platforms, my next step is to complete an optimised port to the Blackfin. Several alpha testers have confirmed that Oslec already works far better than the Zaptel echo cancellers, closer to HPEC in terms of performance.

    Cheers,

    David

  • david

    Hi Bruce,

    You know I am also getting some getting some questionable audio quality on the prompts when I use them for testing – especially when I daisy chain several ports like IAX2 – FXS – FXO – IVR.

    It could be the GSM codec, not sure. I have messed with mulaw prompts in the past and will probably re-install these on the IP04. With 256M of flash we have plenty of room.

    Thanks,

    David

  • Bruce

    Hi David,

    In our rather extensive testing when trying to develop an ambedded IVR application based on Astlinux and the Soekris 4801, GSM was out of the question as a codec- the quality was amazingly bad. We went instead with G711 ulaw, which improved the audio quality a bit, but it still breaks up, crackles, drops out and so on, not to mention fuzzy sound when it’s not breaking up. Again, this is on pre-recorded prompts\greetings in an IVR application – not when 2 callers are connected live. We’re about ready to give up on Asterisk\Astlinux just because of the poor audio quality. I keep asking some of the folks in the asterisk community the same question – what good is all this if the most basic thing about telephony – the audio quality of what a caller hears, is poor?

    Having said that, I’m most interested in your project, and wish you the best. If you need some high quality prompts\greetings for your testing, let me know.

    Bruce

  • David,

    The GSM codec shouldn’t be a problem. It is implemented as fixed point in every case, so it should run pretty fast on your blackfin box. Its much more likely a filing system thing. There probably isn’t enough material read ahead to ensure audio is always available to play at the deadlines.

  • Roy

    Hi David,

    Amazing project! I like it! And I was looking for similar solution for my project in Africa. Let me know as soon as you are ready. We can market this product in Africa for SME and SOHO.
    Just a little bit about my project: We are developing a Wireless Municipal based on Wi-Fi and WiMAX in Africa. The VoIP is the key service for this project. So I am looking forward to hear about your progress.
    Cheers

  • [...] Building an Embedded Asterisk PBX Part 3 – Original Link. [...]

  • I wonder if that skipping problem relates to a problem a number of people get with FAX. I’ve had a number of reports from people for whom rxfax works well, but txfax always fails. rxfax only requires a V.21 modem to work on the transmit side, which is pretty forgiving. txfax requires the image modem to work, and any skipping there is fatal. It doens’t happen when I test with my machines.

  • [...] Building an Embedded Asterisk PBX Part 3 – Link. [...]

  • Hi…I think the $400 price point ($100 per port?) is very reasonable. Sound quality is definitely an issue…it needs to be good.

  • david

    Thanks Larry. I should point out that I haven’t had any big problems with sound quality yet – just the GSM prompts when cascaded (daisy chained) through many analog ports. I haven’t put any effort into tracking down the reasons yet. I doubt it will be a show stopper.

    I suspect that will be fixed with the new echo canceller and switching to mulaw prompt files. I think most of the comments above refer to Bruce’s experiences on a different platform.

    Thanks,

    David

  • Bruce

    Hi All,

    I should point out that the sound quality issues we’ve been trying to deal with have occured on different kinds of hardware – including (1)an embedded device and (2)rather powerful PC’s, with different “flavors”of asterisk, including Asterisk itself, Asterisk@Home, Trixbox, Asterisk Now and Astlinux. The sound quality problems also occur on several different voip connections, pstn or pots connections (using several different pieces of hardware to give us pots connectivity) and softphone on the internal network. And, these sound quality problems occur when there is only one caller on the system – not only when the system is handling several callers at once. The only common element in all these tests is Asterisk itself. Again, this is when playing a series of short pre-recorded sound files in an IVR application – not when connecting two live callers together.

    Kanti- thanks for those links – I wish there had been more of an effort to identify why they were getting the good sound they referred to in those posts. I found just the opposite. But I’ve spoken with the creator of Astlinux, and he didn’t offer any advice. At the moment, I’m seeking help from Digium. By the way, I am assuming that by “native sounds” they are referring to G711 ulaw sound files. With the various VOIP providers we have tried, most support ulaw with no transcoding required on the cpu of our device. Other codecs do require CPU time to make the conversion. I assume the thought is that the less your CPU has to do, the better the sound quality will be. Many voip providers also support GSM, I believe, but our tests showed ulaw to be far higher quality. Someone correct me if I’m wrong on any of those points.

    Just want to be clear that I’m not being negative about David’s project – I could end up being a customer for his device! I’m just bringing up the sound quality issue because it never occured to us to be concerned about it, and then after months of development work on our IVR application, and a considerable amount of money spent – we found that the audio quality is so poor that we can’t sell the product to anyone. In hindsight, we should have checked the audio quality first, then gone on with the development of the IVR application. I’ve had traditional IVR applications (Windows-based using Dialogic or Rhetorex cards) for years, with outstanding audio quality. It never entered my mind that I should have checked any audio quality issues there might be with Asterisk before proceeding. I learned a valuable lesson!

    Bruce

  • david

    Thanks Bruce. You have me curious now about this prompt quality issue! I will look into the prompt quality issues some time over the next few weeks and report back. In the past I have used mulaw prompts on the Blackfin with good results, but I too have found the GSM prompts to have a few pops and clicks. Not sure why. Like you Bruce I have had some great IAX2 phone calls with GSM codecs, comparable to G729.

    BTW some speech codecs don’t work as well with higher pitched voices (such as females and children), it’s to do with the way they model the pitch of the human voice.

    One other possibility – there could be a bug in the GSM codec for Asterisk, for example perhaps it is being overdriven (incorrect levels). Just a thought. Seems unlikely given the number of people using * these days.

    Cheers,

    David

  • Hey David,
    I first came across your project last year but thought it was too low level. But of late, the normal telephony stuff has become dry. I noticed earlier further up the top you mentioned that the BRI daughter board project requires some developers. If you could email me or call me to discuss the possibility that would be grande.

    Great work thus far!

  • David,

    A LPC based codec without fractional picth estimation sounds warbly for high pitched voices. I can’t see how that effect could be described in the way the current problem has been described.

    In the only real test I was able to do where someone complained that txfax never works but rxfax always does, I got an audio log of what was sent out. That log was perfect, yet the fax could not be decoded at the far end. It appears something makes the outgoing audio stutter on some systems for audio originating within the box. The same machine that could not use txfax could send faxes OK if they came through the box from an iaxmodem/hylafax setup.

  • Bruce

    Hi David,

    I’ll be interested to see what your experiments reveal regarding audio quality. I agree with you – that one would think the sheer number of people using Asterisk would have to mean that it performs well. But I’ve also been told by several Asterisk experts that the audio quality will never be at the level I am expecting – and that Asterisk users are willing to endure the poor audio quality because of the cost savings involved. Those are their words, not mine. In my mind, it’s not such a big deal to play audio on a phone line – I’m unclear why it should be such quality issues. And beyond that, fuzzy sound may be one thing, but pops, clicks and drop-outs are another. Please let me know if I can assist your experiments in any way (I record telephone audio for a living), and good luck with your project!

    Bruce

  • Hello,
    We are located in the suburb of Boston. MA. I am very intereted in a partnership deal for promoting and selling your commercial version of PBX. Let me know when it will be ready and the pricing structure. How does it differ from the current prototype version – just packaging, automatic power up and run without any manual intervention etc ?
    Shivram shetty
    President,
    Starburst Business Technologies
    http://www.starburstnet.com

  • david

    Hi Shivram,

    I anticipate there will be two releases over the next few months, the first an assembled PCB, the second production harwdare in a box. The goal for the production hardware is “dial tone out of the box”, i.e. you switch it on, pick up an FXS extension and you are ready to go. Some sort of GUI will be used for configuration.

    Shivram, before we discuss commercial terms please tell me how you and your company will contribute to the Free Telephony Project? If you are to derive commercial benefit I would really like to see some sort of contribution, for example help with the software development or sponsering others to do so.

    This will be a question I will ask to all potential business partners. How are you going to help us? Any contributions must be open (free as in speech), and obligation free.

    So far we have had several such contributions from commerial companies, for example:

    + donations of test equipment
    + direct support of engineers developing open hardware and software
    + free assembly and parts for hardware prototypes

    This is a community project and we are looking for partners who can contribute to that community. This is a little different to traditional business relationships that are based soley of mutual profit. While we are happy to have people profit from our technology, we also ask that they contribute. In return, we can offer our full support.

    Thanks,

    David

  • david

    Interesting Feedback! :-)

    I found this thread discussing this project. This is really interesting user feedback for me. The take away is “cool, but too hard”.

    I quite understand guys – thats why we are working hard to make this technology easier to use and hack:

    1/ The Astfin distro makes embedded * as easy to build as a x86.

    2/ We will soon have assembled hardware that has “dialtone out of the box”, and the * 1.4 GUI for easy configuration. If you want to dig deeper, uClinux and * are under the hood ready for hacking :-)

  • Robert Vogel

    Looks like a good project.

    I have a question that’s a little off topic. There are a number of locations in my area where wireless internet is public and free. My impression is that the internet is just a big pipe and that I should be able to make a phone call from these locations using VOIP. Is there any reason why there cannot be an open source phone that could dial from free wireless locations ? Is there a law about it ?

  • david

    Hi Robert,

    Apologies for my late reply. I don’t know of any laws, and I really like the idea! I would like to see all phone calls free via just such an infrastructure.

    Cheers,

    David

  • That depends on where you live. Various countries prohibit or limit the legal use of VoIP.

  • David B

    David,
    At $400.00 I think I will take at least 3 of them. Any basic PC will cost at least $500.00 and then I will need add some FXS cards to it. I don’ think it can be beat. People also have to take notice that you have worked hard on your own to develop this technology on your own time. We all appreciate that.

  • Hello David,
    we are an algerian company, we found your project very interessting,we want to try the IP04, i know it cost 400 USD,wich is little high for us in Algeria, but still want to try it (with 4 FXO or more FXS/FXO).
    can you please provide us with a list of distributor of the parts to try get the prices lower.
    thank you
    best regards,
    nabil

  • david

    Hi Nabil,

    In the IP04 hardware SVN there are a couple of BOM spreadsheets that have part numbers from companies like Digikey. See the IP04 page for links to SVN. I encourage you to build your own copies of the IP04 locally to suit your local market.

    - David

  • Robust

    hi, David!

    I can not cantact you by david@rowetel.com. Could you please send me a email? I have something to be discussed with you.

    Robust

  • Elton vd Walt

    Hi David

    First i have to say thanks to people like you, i think that what you are doing is great and inspiring to the rest of us.
    I only have a basic to intermediate knowledge of hardware and linux but two friends and myself would really like to give this project a go.
    I have someone that said they could get the IP04 board built for me, all i need to do is give him the gerber files.
    I know this may be a bit forward but would it be possible to send me the gerber files or maybe post them on your site.
    In the meantime i am putting a linux pc together and getting to know the Geda tools so i would eventually be able to generate the files myself.
    If our production cost of the boards work out less because of the exchange rate maybe we can facilitate to have the boards built here and shipped to wherever you need them sent.

    Do you have a current wish list regarding donations ?

    Regards
    Elton
    South Africa

  • Nigel

    Hi David,

    Firstly may I just say well done, your project has opened up so many possibilities within the wireless VoIP market.

    We would be very interested to hear from anyone who has or is running tests using the IP04 with IAX on wireless networks.

    We are looking for the best use of the available bandwidth in our mesh network systems in rural Spain and Central America, we are currently using SIP and SPA 2102s.

    We would be more than happy to collaborate with like minded people.

    All the best,
    Nigel

  • Heydait

    Hi Dear,

    It is really great to see such projects. I am currently working on Avaya VoIP System. I would like to know the procedure and details that how can I purchase this projects.Please provide the contact details.

    Regards,
    Heydait

  • david

    Hi Heydait,

    You can buy hardware from the Free Telephony Store

    Thanks,

    David

  • That log was perfect, yet the fax could not be decoded at the far end. It appears something makes the outgoing audio stutter on some systems for audio originating within the box. The same machine that could not use txfax could send faxes OK if they came through the box from an iaxmodem/hylafax setup.

  • Anang

    I need more infomation or case study of Cisco IP PBX system connectiong Analog Telephone

  • Rupesh

    hi thanks
    i am new to blackfine and uboot where i can find the u boot and bsp for bf532 board.
    we are having the pcb from your organization.
    thanks
    Rupesh

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