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Cross-Platform Internet Telephony?
the . Silicon . Dragon writes: "The company I work for is creating a product that we hope to launch on Linux. One of the key features of our product is Internet Telephony where a user can not only call other users on the Internet, but also make and receive calls from standard telephones. We've investigated a number of possible solutions, but they all have shortcomings. The most sour part of the situation is we may have to move our launch platform to Windows if we cannot find an acceptable Internet telephony solution. It'd be highly disagreeable with myself and several others in the company as well if we have to do this, but we can't drop a key product feature and we don't have the time or the resources to develop the technology in-house. Suggestions for Java (preferrably) or C/C++ solutions, and/or references to companies that provide said technology would be extremely helpful." The 'key feature' in question is interface customization. You can find out more in the article.
"It is an absolute MUST that we be able to customize the interface of any such client application. Second, it MUST be able to run on Linux and Windows with minimal pain (the product is coded in Java). Lastly, the quality MUST be fairly high. So far, solutions like HearMe and OpenH323 are either incomplete, lack quality, are not cross platform, and / or do not allow us to create our own interface."
http://www.speakfreely.org/
Hey, Ask Slashdot editors: Could we get a slightly higher quality of question and less repetition (we've had the "internet camera" question at least twice).
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Linux MAPI Server!
http://www.openone.com/software/MailOne/
(Exchange Migration HOWTO coming soon)
http://www.linuxtelephony.com/
is a good place to start.
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A lot of the big guns out there are busy developing infrastructure that will allow reliable Voice over IP, real-time video conferencing and other delay-sensitive apps to work reliably.
Cisco's Packet magazine had an article on this a while back (it was the cover story on the last issue). I'm sure there are dozens if not hundreds of other articles on this too.
You will see Voice over IP a lot more in the next few years, simply because it's cheaper to implement than traditional, circuit-switched telephony. It's not a bad thing, really, because the telcos are going to have to make it work 100% of the time. That's the #1 concern. People have been getting dialtones all across this continent for 50 years now. It's simply not acceptable that suddenly you only get 9 out of 10 dialtones. It's got to be 100% or it won't fly.
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Quicknet has a low - cost 1 port card that will do the trick with Linux and Windows drivers:
http://www.quicknet.com
Also check out Pika for 4 port cards with traditional analogue and VoIP capabilities with Windows and Linux drivers:
http://www.pikatech.com
Aslo check out the Bayonne project. Linux based Open Source telephony system with interfaces to Quicknet, Pika, and other cards:
http://bayonne.sourceforge.net/
Voice over IP isn't something new. Been around since at least mid-1998. There's a reason - it's not good enough. I speak from experience. I was responsible for the deployment of a national VoIP network using a strictly hardware based solution. And it sucked. Flat out sucked. Going international to a single POP across the Atlantic was even worse, even with a PVC on PanAmSat.
Flat out, TCP is too unpredictable, and not enough solutions are carrier class. There are very stringent requirements for carrier-class quality. And TCP/IP is NOT carrier class. Oh, sure, you can claim it just by slapping on a -48V DC powersupply, but it's not carrier class till you can give *proven* 99.999% uptime, AKA Five-By-Nine(s). There is absolutely *no* VoIP solution that can do this.
Furthermore, MANY VoIP routing solutions are entirely dependent on the H.323 or H.323v2 pseudo-standard, which uses UDP - an inherently unreliable transport - to transmit and recieve call routing information on a per-system per-port level. H.323v2 is also bandwidth intensive. And I have yet to see a system that can interconnect H.323v2 with SS7, which is the absolute standard for all telephone call routing, as defined by Telcordia/BellCore. The Lucent 5ESS runs SS7 for routing, I shouldn't need to say any more than that. This may have changed in the time that I have been out of VoIP, but I doubt it.
In order to bring VoIP to carrier quality, basically, a new routable Layer 3 protocol with inherently reliable transports would have to be created, and all compression schemes would likely have to be eliminated. The compression inherently damages quality, well below acceptable levels for anything useful. Testing a 33.6k modem over a VoIP routed line resulted in 4800 connects at best. The compression causes gaps in conversation, and only increases with latency.
As latency increases, call route reliability decreases exponentially, due to H.323/H.323v2 utilizing UDP transport. Packets are dropped and not retransmitted, resulting in incomplete or lost call route instructions. Suddenly that call to Grandma in Houston, TX from your house in Boston, MA, can't be completed. And bandwidth is choked quickly. Two PRIs worth of circuits used for incoming/terminating VoIP calls will eat a full 6Mbit pipe quickly.
Cisco claims or claimed that the AS5300 equipped with Voice over IP blades had 5:1 audio compression with minimal quality loss. While people were understandable, gaps in the conversation were also very audible, from dropped packets or other inevitable network issues. At a supposedly 5:1 compression ratio for the data transmission, I saw a single call eat nearly half a megabit. A PRI is basically 24 voice channels versus 24 data channels. In effect, a T1's worth of voice channels, using digital format versus standard analog, allowing 24 channels to be carried over four pair copper.
To claim VoIP as carrier class is similar to claiming that a PC at the store is carrier class. Or that just because a system has a -48V DC powersupply, it is carrier class. As I said above - carrier class is defined by reliability, not just feature set. I honestly don't know whether or not any of Cisco's equipment qualifies as carrier class - for certain, in my experience, I would be very uneasy about slapping that label on their Voice over IP equipment.
Furthermore, as everyone gets 'hip' to VoIP, the market is becoming flooded with companies. And much like has happened with so-called 'e-tailers,' there's going to be a purging. Those with the real brains, the right technology, and get in at the right time might make it. Those that don't, don't. IMHO, the time to get in has already passed. It takes time to build a massive data network to begin with, much less research all the equipment available in order to find a reasonably reliable combination.
The PC solutions are no better. The quality is horrific at best, after seeing probably close to 90 different 'solutions' that were anything BUT. They are unreliable - the hardware-based solutions even moreso - and offer very very little quality, much less return on investment potential. I spent a lot of time at a PC trying to get one particular card to work and watched as the card itself gave up the ghost and shorted out itself, due to extremely poor manufacturing quality.
My recommendation? Abandon the idea and cut your losses while you're still ahead. There are other options out there with better profit potential that aren't reliant on a killer IPO performance. Maybe there'll be a maturing of VoIP technologies - maybe even a standardization (HA! Yeah RIGHT!) in the coming years, but now is not the time or place to try it.
=RISCy Business
your company here.
shelby != ford