Flash Based Click To Call

Here's a click to call applet from Russia that's been built in Flash:-

http://www.flashphone.ru/

Flash is is of course well supported by all the major browser platforms (and it'll probably even work on Apples new iPhone). Unlike Java applets, Flash applets do not need to be "signed" to take control of your soundcard, which means no clicking on a "Allow/Deny" dialogue when the applet wants to initiate the microphone.

The bad thing about Flash is the fact that version 9.0 (the latest) still can't do UDP. That means this applet is using TCP for the audio streaming, and that means latency.

TCP comes with a hand-shaking overhead that makes it unsuitable for most real-time two-way audio applications such as a telephony. As well as that additional overhead, TCP/IP operates a "blocking" model. Each end of a TCP/IP connection is prepared to sit and wait for an expected data packet to arrive. This is inherrent in the design of TCP/IP (it has a military communications background) which was never intended to handle voice or other realtime media.

UDP on the other hand is non-blocking in nature - packets can arrive at any time and in any order. The receiving end needs to be designed to anticipate that and re-order or just drop packets accordingly, but there's no waiting and no hand-shaking overhead.

You may have noticed this effect when accessing a website (the web HTTP protocol is TCP/IP) - sometimes you click on a link and wait a good few seconds for the server to respond. Fine for web, file downloading and emails, but not so great for realtime media.

TCP can be made to work for realtime media by using multiple sockets running in parallell (Skype do exactly this) as mentioned before when we looked at Ribbit. If the Flashphone folks want to do something like that, they'll need to keep an eye on patent infringement - I remember Alan Duric telling me back in 2003 that Skype had to do some kind of a deal with a patent holder to enable them to utilise the idea.

Tom Keating has some info also and ran a few test calls. Interestingly, Tom picks up on the fact that there's been a space reserved for advertising, which means at least these guys have thought about the businses case for their product and have a means to monetise it.

Quote:

Just before the call was connected I did see a popup saying something like "Insert Advertisement here

Alec Saunders also picks up on this one and comments that it's probably OK for a localised PBX environment where latency, on your own LAN, probably isn't an issue and even TCP/IP can run fast enough to be entirely usable.

So for local/internal intranet type sites these kind of Flash phones could actually work quite well - click to call systems for internal calling over a private branch trunk perhaps.

For internet use, this will work, but your experience with it will be pretty hit and miss. Tom Keating noticed the latency but found it to be useable. One of our moderators, Mazilo, tried it and found it to be hopeless.

Don't forget that Adobe hired Dr Henry Sennriech last year and part of his remit there is to build a SIP stack for Flash 10. Flash 10 will also do UDP. That's due for release in Spring 2008, although it's been delayed twice already, but if you need a low latency system for wide-spread internet usage you might be better off waiting.

Dean

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