Solved

How Do I Emulate Picking Up the Phone and Dialing 9 With a Stand Alone Modem (no PC intervention after programming)

Posted on 2004-10-19
20
1,177 Views
Last Modified: 2013-12-27
How do I to Setup a Modem to Auto answer without the modem tone, pause, then dial/send a long DTMF 9 and store these commands in one or more S-registers?   S-registers may not be the what I want, I'm just fishing here.

What I want to accomplish is to program a modem's NVM, so that no PC is involved afterward, to answer an analog line without the customary modem tone, pause, then send a long 9.  In effect,  I want to emulate picking up the phone and pressing 9 with a modem instead of a handset.

I tried this with an answering machine, by recording and playing back "9" in my outgoing message.  But the DTMF tone didn't register with the device listening at the other end for the tone.  So I'm curious about this too.  Is there a meaningful, distingishable difference between a recorded tone and one that is inline with the connection?
0
Comment
Question by:JHMarshIII
  • 5
  • 5
  • 3
  • +5
20 Comments
 
LVL 5

Expert Comment

by:AutoSponge
ID: 12385713
Buy the telezapper (or similar product) from Radio shack or similar phone wares supply department.  I'm pretty sure it does exactly what you want and won't cause the problem of answering your phone before you do (only to have someone sitting there waiting to talk to you and never getting you or your answering machine).
0
 

Author Comment

by:JHMarshIII
ID: 12386141
Telezapper doesn't allow you to program it to send a specific DTMF tone.  I know a modem can, but I don't know how to program it as such.
0
 
LVL 14

Expert Comment

by:JohnnyCanuck
ID: 12386258
I can't help you, but maybe this info will get you started.  If I remember from DOS days, you usually start with AT and then the command sequence.  See these 2 sites.

http://www.zoltrix.com/support_html/modem/USEMODEM.HTM#Using%20AT%20Commands

AT commands

http://www.modems.com/glossary/extend2b.html
0
 
LVL 4

Expert Comment

by:Analog_Kid
ID: 12386306
This should be possible using a modem, but I have some questions;
What is the make and model of the modem you want to program?
What is to be done with the connection after the call has been answered and the dtmf signal is sent?  
0
 
LVL 20

Expert Comment

by:jmcg
ID: 12386704
I think you're asking more of your modem than any modem I'm familiar with can deliver.

1) "Answering" a call normally means that the modem will begin negotiating a data connection. There's no place for additional commands to come if you don't have a PC attached.

2) With a PC attached, you can monitor the modem to see when an incoming call occurs (the modem should display "RING"), direct the modem to go off-hook, and blind-dial a tone without waiting for dial-tone. You may be able to set the tone length (S11 if I remember correctly) long enough to effect your purpose.

If your recorded tone did not cause the other end to respond appropriately, there may be something else going on. A recorded tone should work just as well as one generated by your modem, as long as the frequency isn't shifted by more than a few percent.
0
 
LVL 4

Expert Comment

by:Analog_Kid
ID: 12387592
If the answering machine uses analog tape to play the outgoing message, chances are that the tape is poor quality. Replacing it with a fresh, high quality tape may yield better results. Iron oxide, and chromium oxide tapes have differing characteristics - experiment with each to see which produces the best results for that particular machine. I'd also suggest a cleaning; tape head, capstan, pinch roller and tape path.

Unfortunately tape machines are not hi-fidelity sources. While they may be fine for voice recordings, the tape is very narrow, and it moves very slowly. There are also inherent bias distortions. The effect of these factors is to reduce the amount of signal that can be recorded. Also, slight variations in the playback speed relative to the recording speed can alter the frequencies to the extent that the dtmf tones will be out of tolerance and unrecognizable by the device at the other end.
I believe a digital device would be better suited to this application.  
0
 
LVL 12

Expert Comment

by:public
ID: 12390130
>I believe a digital device would be better suited to this application.  
Not the cheap answering machine kind. Even VoIP has problems with modems and faxes unless the highest quality codec is used.
Something like good quality mp3 player may work.
0
 

Author Comment

by:JHMarshIII
ID: 12390287
To answer "jmct's" two questions:

>> I'm using a 3Com/USR External 56K Voice Faxmodem Pro

>> After the auto answer, "blind-dial tone", and send long DTMF 9, I'd like the modem to just disconnect and make ready for the next call.

On "Analog Kid's" feedback:

"If your recorded tone did not cause the other end to respond appropriately, there may be something else going on. A recorded tone should work just as well as one generated by your modem, as long as the frequency isn't shifted by more than a few percent."

>>  I'm using a Siemens digital answering machine.  The device I am trying to trigger is a switch of some sort listening for #9.  But the digital answering machine didn't work.  Doing it with a telephone though works perfectly.  That is why I think a modem would work.   Doesn't a DTMF tone sent by the keypad of the phone also disrupt the open circut somehow.  Could this be the missing element the device is looking for, perhaps to thwart an audio dialer?  Sort of an in-line DTMF.  (This is not a public network, it is an intercom system tied into the phone line under my control.)  I imagine that this switch is very sensitive to the proper frequency, with any kind of recorded tone falling short.

If I can't do this without a PC, I could add it to the mix.  But aren't these AT commands that can be stored?

On" public's" feedback:

>> I'm not quite sure how I would auto answer with a MP3 player.
0
 
LVL 20

Expert Comment

by:jmcg
ID: 12390384
I think you're mis-attributing our questions, but we get the idea anyway.

The AT commands are something that might be stored on the PC. I'm not familiar with any modem (of course, I've never worked with one of these "voice" modems) that can record a sequence of AT commands and play them back in response to an incoming call.

The modem's DTMF generator is likely to work as well as a phone's, which may get you past the difficulty you're experiencing wth the recorder. No, the tones are sent over the established voice circuit in-line -- there is no disruption or break in the circuit which the other end could be depending on.

For a PBX system, however, it could be that some other signaling method is being used. This was why, a decade or more ago back when people with laptops and modems were uncommon, many hotels had phone systems that you could not dial out on using your modem. Can you plug a regular phone (like you'd use at home) into your private phone system -- and does it work for this #9 signal, too?
0
What Security Threats Are You Missing?

Enhance your security with threat intelligence from the web. Get trending threat insights on hackers, exploits, and suspicious IP addresses delivered to your inbox with our free Cyber Daily.

 
LVL 31

Expert Comment

by:rid
ID: 12392579
"But the digital answering machine didn't work.  Doing it with a telephone though works perfectly..."

This sounds like a signal level problem. A digital recording/palyback device shouldn't show any frequency drift and would be ideal for DTMF stuff. However, if the recording gives too low output level when played back, it might not trigger the listening device in the other end. The telephone injects the signal directly into the line at a predefined level. Can you adjust playback level of the digital answering machine?
/RID
0
 

Expert Comment

by:aqueeb
ID: 12520973
I am also looking for an answer to this. I want my modem to auto answer after two rings.....send a the dtmf tone for 6 and then hang up waiting for the next call. I tried the answering machine method but the recording played back is too low and there is no way for me to increase the playback volume on the answering machine. I really want to know the solution to this one and would be very grateful.
Thanks.
0
 
LVL 4

Expert Comment

by:Analog_Kid
ID: 12524107
See the links posted by JohnnyCanuck
That should provide you with the information you need to get something working for your modem.

I was not able to find any specific info for the modem in question.
0
 
LVL 20

Expert Comment

by:jmcg
ID: 12729339
The task was over-constrained, so it had no feasible solution. I'm not sure it's worth PAQing, so either delete or PAQ is fine by me. Unless JHMarsh comes back with additional information, I'd argue against a refund.
0
 

Author Comment

by:JHMarshIII
ID: 12736203
jmcg said  1) "Answering" a call normally means that the modem will begin negotiating a data connection. There's no place for additional commands to come if you don't have a PC attached.

jmcg also said "The task was over-constrained, so it had no feasible solution."

Let me begin by removing the constraint of solely relying on the Modem itself.   Hyper terminal is available to control the modem.   A solution to this problem could positively impact hundreds of people that are part of an all volunteer organization.
0
 
LVL 20

Expert Comment

by:jmcg
ID: 12737623
While I suspect there may be better ways to solve this problem, I can envision solving it with pieces that are already in hand or easily obtained.

Many terminal emulator programs have a scripting language. I used to be familiar with the Procomm "Aspect" language. Hyperterm probably has one, too, but it may not be included in the "free" version of Hyperterm included with Windows. If I were doing it today, I'd probably use the Expect language on a Linux system installed on an old, otherwise discardable PC.

Most modems speak the so-called "AT" command language originally developed for Hayes modems. Every modem is a little different and it can be a trick to find the full command reference for your modem. US Robotics is moderately good in this respect. For example:

http://www.usr.com/support/3453b/3453b-crg/appd%202-alphabetic.html

So, it looks to me like you'd set up your modem not to answer automatically, have the scripting language wait to see the string "RING" from the modem, then issue the modem command

ATX3H1D9

AT = Attention
X3 = Ignore Dial Tone (Blind dial)
D9 = Dial number 9

or something like that. Some experimentation would be needed before you got it working correctly and reliably, since we don't know how long the tone has to be played in order for it to be effective and we eventually have to hang up the phone afterwards.
0
 

Author Comment

by:JHMarshIII
ID: 12739275
Thank you jcmt, I will try this approach and close the question awarding the points to you.   I need about a day to fool around with this before I close the question.
0
 
LVL 20

Accepted Solution

by:
jmcg earned 500 total points
ID: 12739381
Oops, I forgot to say the "H1" was to "Go off hook".

Let me know if there's anything else I can do to help!
0
 

Author Comment

by:JHMarshIII
ID: 12739995
I will also provide some interesting backround on this question.
0

Featured Post

Threat Intelligence Starter Resources

Integrating threat intelligence can be challenging, and not all companies are ready. These resources can help you build awareness and prepare for defense.

Join & Write a Comment

Suggested Solutions

 One of the main issues with network wires is that you never have enough.  You run plenty and plan for the worst case but you still end up needing more.  What many people do not realize is with 10BaseT and 100BaseT (but not 1000BaseT) networks you …
This article is a how to to configure a UCS Ethernet-uplink portchannel via the console. It is easy to do and can be done quite quickly. In certain versions of the UCS manager the portchannel has issues coming up and this is a workaround. I am…
It is a freely distributed piece of software for such tasks as photo retouching, image composition and image authoring. It works on many operating systems, in many languages.
In this tutorial you'll learn about bandwidth monitoring with flows and packet sniffing with our network monitoring solution PRTG Network Monitor (https://www.paessler.com/prtg). If you're interested in additional methods for monitoring bandwidt…

759 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question

Need Help in Real-Time?

Connect with top rated Experts

19 Experts available now in Live!

Get 1:1 Help Now