Homemade VoIP Network Over Wi-Fi Routers

AnInkle writes "A blogger on The Tech Report details his research and testing of wireless voice communication options for remote mountainous villages in rural undeveloped areas. The home-built project involves open-source software, low-cost wireless routers, solar power, mesh networking, unlicensed radio frequencies and VoIP technology. Although his research began several months ago, he has concluded the first stage of testing and is preparing to move near one of the sites where he hopes to eventually install the final functional network. Anyone with experience or ideas on the subject is invited to offer input and advice."

Urban Networks...

Wouldn't this be great! You could use your networking skills to setup a private, free telephone system. And, if it was encrypted, no one could snoop in on it... and if it was in an urban environment... Hmmm....

Re:Urban Networks...

And, if it was encrypted, no one could snoop in on it

Hold your horses, Osama, it's not perfect yet :)

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Shrug. Killing the joke, but:

Al Qaeda NEVER uses electronic communications. They communicate face to face, always. No cell phones, no computers, no GPS, no mail, no land lines, nada. This is why I scream madly at every "homeland" security citation about en

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Don't tell me you Actually believe the Anti-Terrorism laws are to do with terrorists.

Re:Urban Networks...

Zero chance. I'd even deem it unlikely that the original project survives for long. Telcos are missing out revenue when you communicate for free, the feds owe them one for the wiretapping thing, so I expect a law soon against this. Because of ... because of ... national security or whatever fits.

Re:Urban Networks...

There are (still?) cell phones with DECT (household grade cordless phone technology) built in. I always thought this would be a much better alternative to a cell phone with wifi built in to accomplish VoIP. DECT is pretty lightweight, so do VoIP to the DECT base station, then DECT to the phone. When you are in range of the DECT base station (eg at your house) you'd make calls via that instead of the more expensive cell network.

Not sure why this never took off... could have something to do with the less money that the cell providers would make.

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"Not sure why this never took off... could have something to do with the less money that the cell providers would make."

Gee, you think?

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BT tried something not a million miles from this in the UK. Went by the name of BT Fusion and the principle was that the compatible handsets used Bluetooth to communicate with a base station (which was also a DSL Router) and thus your mobile/cell phone use

Why not cellular?

Read this yesterday, still don't get it. Can omni directional wifi ever compete with a cell tower's coverage range? Cellular has the advantage of insanely cheap commoditized phones.

Seems a bit like trying to use bluetooth to connect two buildings in a campus together - nominally cheap hardware, but probably cannot be coerced into doing what you seek.

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Insanely cheap commoditized phones subsidized by an insanely marked up cell phone plan. The point of this exercise is to provide the infrastructure where private business currently doesn't feel there would be return on investment. Think OLPC for VoIP.

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Read this yesterday, still don't get it. Can omni directional wifi ever compete with a cell tower's coverage range? Cellular has the advantage of insanely cheap commoditized phones.

But cellular base stations have to transmit at high power. Doing that attracts attention from authorities. Wireless mesh networks can be low power everywhere.

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Wifi has the advantage of insanely cheap communication.

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That's not the point of this research project.

The point is that many developing countries do not have the economical manpower to deploy cellular antennas everywhere, thus eliminating the possibility of many areas receiving cell phone service. This person

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one problem with cell phones is that if the company who builds them doesn't think there are enough people in the area then that area doesn't get a tower.

there are still huge sections of the USA who can't get cable TV as they are to spread out for a cable c

Re:Why not cellular?

I think the main drive according to the article is the 802.11x frequencies tend to be de-regulated and free to use, cell networks have ongoing fees to use that portion of the spectrum. Also wireless routers have very low power requirements and can be run via hippy fuel (aka solar) instead of some poor bugger having to run the mother of all extension cords up a mountain.

Re:Why not cellular?

FTFA,

Technology alone is not sufficient. For any project like this to work for more than a couple of years, it must have a sustainable business model. (In the long run, at least as much money needs to come in as is going out.) Village Phone, which builds on traditional cell phone technology, has been very successful in bringing communications to rural Africa. Their model, in summary, involves an entrepreneur from the village purchasing a cell phone, roof antenna, and charger with the help of a microloan. They are then able to sell minutes to villagers for a profit. The cell phone antenna must be within about 35 km of a cell phone tower and have line of sight, thus making the technological aspect of this model unworkable in many rural or mountainous regions.The business model, however, could potentially be used just as successfully with other technologies, including WiFi paired with VoIP.

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Why not? Easy, you could give your kids an old PDA or hacked Skype phone or something for use around the neighborhood without having to pay an extra phone bill.

In a somewhat similar vein

David Rowe [rowetel.com] has been quite busy working on cool, low-cost telcomm stuff. His site also has links and comments and so forth from others interested in the subject, including people doing actual, in the field, deployments in fairly poor and hostile(to the tech) environments.

mountains and wireless

the two do not mix well, mountains will severely block radio waves from any part of the spectrum...

relays

...when strategically placed can deal with that.

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they better put repeaters on the very tops of the mountains that they need to get over...

Tried something similar... didn't work well

I experimented with 5 units of WRT54G wireless routers running Freifunk firmware [freifunk.net] and I tried saturating the link with several G.729 VoIP calls. The system doesn't scale well. Over 3 hops, the number of calls greatly reduces as there is just too much random delay. In order for voice communication to be worthwhile, the latency cannot be more than 200ms although there are good forward error correction schemes and huge buffers.

Latency is a real problem especially when you are doing it over several hops. The "lag" isn't consistent. It will hit you at random interval, and that can be extremely irritating. This may be due to the use of CSMA/CA and RTS/CTS (depending on configuration). I haven't found a way to improve it though...

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Over 3 hops, the number of calls greatly reduces as there is just too much random delay.

Yes, there are a number of issues with building multihop mesh networks over wifi.

If you're using omni-directional antennas, the most serious issue is that the multi

i know someone

Anyone with experience or ideas on the subject is invited to offer input and advice.

http://img368.imageshack.us/img368/5753/macgyver2rs.png

overhead

This brings me to a thought I have every time someone wants to know if they have enough bandwidth for voip. How much of h323, voip, etc.. is consumed to keep the whole accounting; pay per call, distance of call, who is calling, etc.. type stuff together? It seems to me a constant open stream where audio could traverse in any direction and any distance would not be that bandwidth intensive. Maybe I just don't understand everything involved.