[Asterisk-Users] AGI and fast-entered DTMF codes

[Steven Critchfield]

On Wed, 2003-02-26 at 16:40, Alan Murphy wrote:
> Hi Stephen,
> 
> I tested the system using both a desk phone and my mobile phone. The
> mobile phone had no problem, no matter the time between key presses, for
> the reason you mention below (it sends the tones for a specific and
> consistent period of time). The desk phone did not do this and thus
> resulted in the problem. As for the actual speed between the tones, I'm
> afraid I couldn't measure that, but it was quite fast with no pauses
> between key presses.

Thats fine, didn't expect you to be able to measure it. The no pauses
raises a bit of concern. There is supposed to be a set time between
keypresses.  

> When I noticed this, I knew that I could either send the tones in a
> reasonable amount of time, or use a better phone. Unfortunately, we are
> bound to get users who will type fast and wonder why the line has gone
> dead on the other end. We are running a small competition for people
> here, so have no control over their type of phone. 

If they are typing fast due to a contest, chances are they already know
that they can type faster than speed dial, but they can outrun the telco
and have problems. This is something I did back when I tried to win
things from the radio stations. At one point I started using a modem
that I could tune the pause and tone length till I was getting only
about 10% failures. The time to dial was significantly faster.

> I tested the desk phone with a well known phone banking service here
> (which requires DTMF tones), and it had no problem with fast sending
> from the phone. It could be the hardware involved, I suppose. I thought
> initially it was a buffering problem in Asterisk. The X100P driver could
> be sending garbage to the application if it cannot decipher the tones
> quick enough, thus resulting in the problem. When I get more time, I
> will delve deeper into the code and attempt to find the source of the
> problem. I thought someone else might have encountered this and would
> save me some time :)

If it isn't recognised as DTMF, it is sent as audio. There wouldn't be
any garbage.

> As for Java as a scripting language, I do most of my development in it,
> so it was a matter of convenience. I also had reusable database code to
> access some internal data that is required for this project. You are
> right about scalability, though. The AGI script will create a new JVM
> each time it is run. A lightweight client (in a language other than
> Java) that establishes a connection to a multi-threaded Java server
> would allow scalability, but that sounds like a lot of work for two
> incoming lines :)

Good, you didn't see that as the begining of a language holy war. For 2
lines you are correct it should be plenty enough. As for the idea of
building a multi threaded java server, do you want to tie the system to
another single process that could fail and take all lines down with it?
We have a app we have been working with, and rather like the idea of the
app starting and dieing on a per channel/per call basis so as to make
sure the system is always respawning a fresh copy for a call. Our
current software has threads that hang occasionally and tie up the phone
line till we interactively reset it. This is why I spend so much time
with asterisk since it will eliminate that interactive reseting. 

-- 
Steven Critchfield  <critch at basesys.com>