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Domain: openphone.org
Stories and comments across the archive that link to openphone.org.
Comments · 8
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Re:We need an Open Source Skype
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suggestionsWill Linux Telephony do the trick?
If how about useing Speak Freely or Open Phone?
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easy problem--easy solution
Well, voip isn't very complicated. If you're unsatisfied with the currently available solutions like those available at LinuxTelephony or OpenPhone you can always roll your own. I know I'd lay down a couple bucks for a satisfactory one, so you can probably sell it and make a couple quick bucks from your effort, too. Stop whining and make a difference!
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Re:OpenH323OpenH323 is an incredible project. It is more stable than most commercial grade H323 stacks when it comes to audio (H323 includes video also - think NetMeeting). Its really strong points are:
- Crossplatform - runs on Windows and *nix (Im not sure about Max or Bez et al)
- It has been tested and interoperates with more H323 stacks than you knew existed - Radware, Cisco...
- Free Software - which is the point of this article, right?
There are some problems with the H323 specification in general though. For example:- Very complex
- Control data is transmitted in binary form - most widely used protocols are based on ASCII (FTP, HTTP, SMTP)
- It uses a port assignment process which is virtually impossible to use through a NAT firewall.
There are of course many options in the VoIP world right now - SIP is a protocol that works to simplify the processes of the H323 stack. As far as I know, there are a few different implementations of SIP and none of them work very well with each other. You can read more about it here.
A friend of mine has written some very good articles about Linux and Internet Telephony:
Linux Journal Article
SVLUG Presentation
I personally think that the best solution right now in terms of interoperability, quality and Free-as-in-speech-ness is OpenH323 with OpenPhone. Our company uses a combination of Quicknet PhoneJACKs, OpenH323, and a few CIPE VPN tunnels to connect people from CA to Texas to Australia at their Linux boxes using real-live ringing phones - at essentially no cost. Quality is very very close to a typical old-guard phone call, even from San Francisco to Sydney over the Internet, _and_ encrypted. Blows my mind whenever I use this stuff. The Quicknet cards have GPL'd drivers and are in the current kernel tree. They seem to add a ton of power to the call by offloading alot of the work to hardware DSPs. -
Some info
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Not True! It works over dialup!You do NOT need ultra-fast connections to do Internet Telephony. If you use a software only solution (using your sound card) you can compress with GSM and take the 64kbps audio stream (one way, 8khz samples at 8 bits each) and get it down to about 9kbps or so. You add latency due to the time it takes to do the compression. If you have a hardware compression device (such as what my company makes) then you can use better (and more standard) compressions like G.723.1, or G.729a. These can get down very low (5.3kbps for G.732.1). And since it's done in hardware, you get very little increase in latency. The most important thing is that you get to use the compression codec with the license paid for by the hardware vendor. Thus, open source projects can use this technology without issue regarding the intellectual property and royalties regarding the advanced compression codecs. And you can plug a real phone (such as a cordless) into your PC and it acts like a phone because it is a phone!
Remember - that's one way! You need to add the reverse direction, and then add the packet overhead of RTP (real time protocol) and UDP, plus the control signals. You can do great IP calls and use about 16kbps or less. I know. I do it all the time!
Our products (PCI/ISA/PCMCIA) allow you to connect a normal phone to your PC (and provide dial tone, DTMF, ringing, etc) and provide the compression codecs. We have open source linux drivers, and are in the kernel as of 2.2.14. For more information, write me or see our web site: Quicknet Technologies, Inc.
Check out the OpenH323 Project and the OpenPhone Project for more information.
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Re:telephonyThere are several VoIP solutions out now. The most useful one is part of the OpenH323 Project. There are several applications in the package: the basic test app called Voxilla, and the more interesting app called OpenPhone. The latter is the "flagship" application of the OpenPhone Project.
These applications run on linux (and Win32) and work very well, even over dialup connections. If you use hardware to do the audio compression you can use a normal phone and get MUCH better performance. Disclaimer: my company, Quicknet Technologies, Inc. makes this kind of hardware. We even have open source drivers, and are in the kernel as of 2.2.14! We're hiring too!
Internet Telephony is the next big thing - and linux will be a major platform for it.
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OpenPhone / OpenH323There are more Internet Telephony options available, and encryption is an option in many of them.
The OpenPhone Project aims to make it easier for this kind of software to get built. Other good links include: