atcomsystems.ca/forum Forums Computers & Programming Computers, Software, Accessories Modem commands

I have a problem with my modem working under Procomm, ECom and HyperTerminal. It dials the number programmed, pauses accordingly, dials the necessary additional digits but then drops the call. I can monitor it and hear the call progress and everything seems fine.

I've tried AT&F, ATZ and I've even set it for X1 so that it doesn't monitor for dial tone. I've also verified that all other settings are correct.

I'm using ATE1Q0S11=200S8=13X1 as the initial setup string after AT&F.

This has been working for me for years. It causes a pause to last 13 seconds and forces the DTMF duration time to be long to dial through auto attendants.

I think that I have activated a command that tells the modem to dial then drop, but I don't know what that is. I still don't understand why initializing it wouldn't clear this, especially when I save it using AT&W0. Any ideas?

Ed -

Can you test it on another line - or on an ICM path or -48V - something just to see if it stays up.

What I'm getting at is maybe it's a line condition from the Telco.

I'll go look for modem commands, but I think I sent them away to that squid in Hawaii who needed a copy of Procomm.

Sam

No, it's not the station port I'm using. I have two different modems sharing the same extension; one works fine and the other does what I described. Of course, I don't try to use them simultaneously.

I'm pretty good with AT modem commands, but when the start getting into the %, / and $ commands, my memory fades. I have Hayes books at the office, but this is for my modem at home where I don't have the docs. I can use my cell phone as a tethered modem for tonight's project if necessary.

I swear that I recall there being a modem command like ATDTxxxxxxx:, and I think that the colon just causes it to stop dialing and await commands from the far end. If that were the case, it's certainly not waiting around for long since it drops the call upon dialing the last digit.

I may just have a bad modem, which is possible. It just seems odd that it does everything else perfectly.

Try ATDT XXXXXXX,,,,,,,,XXX.

No, I already have the comma set for 13 seconds using S8=13. It doesn't drop until after the 13 second pause and the second string of digits for the remote modem's extension number are dialed. It drops immediately after the last digit. It has always worked fine with these settings until recently, so either I screwed something up or the modem is just going bad.

I never use the S8= command. I use a default setting with the string I posted to dial at dial tone and insert however many commas I need to simulate pauses. Modem may be FUBAR.

I would, but Vodavi software doesn't allow enough spaces for that many pauses along with a toll number and a modem extension. I have to force the pause timer long to use their software. Go figure.

Seem to remember you could use L for long pause that would take the place of ,s.

Now you're making my head hurt thinking this late. :scratch:

I remember back when that this symptom was usually due to incompatible compression. The answer was to turn it off, but I do not recall the command.

Ed, the command that puts the modem in so-called "command mode" is ; (semicolon), not :
But this command does not hang up the modem, it just makes it wait for commands from the terminal.
The only other thing I can think of is a security dialback function that is somehow activated. That is, your modem dials in, and then it drops the connection so the receiving modem can initiate the connection as a security precaution.
I would suggest you dial manually through the comm software and see if it goes through.
Also, after the line is dropped, in your comm program, enter ATS86?, this may give you some info (it's the event register). You may have to enter +++ (no AT prefix) before you can communicate with the modem.
Finally in (windows) Device Manager -> your modem -> properties -> diagnostics -> view log (you may also want to check "append to log" temporarily) for some more info.

the &F would turn that off by initializing the modem to facotry default, which should have dialback set to off. He might try AT&E to turn off software flow control.

PMCook, you're right about the AT&F command, though many modems have to be issued the command twice - AT&F0 and AT&F1 so both the chipset (the data pump etc) AND the entire board clears.
Also not all modems have all registers, so ATS86? may not work. Issue a series of info commands to find out - ATI0, ATI1, ATI2 etc etc untill it returns an error. Everyone of these commands gives different info.

I need to check my initialization strings again. I may have a colon instead of a semicolon inserted somewhere, although I have not changed a thing on this computer in three years.

I'll also try the &E idea. What do I have to lose? Thanks to all so far for your input. I need to get this problem fixed, hook or crook, so anything is worth the effort.

Did you try strapping DTR high (AT&D or AT&D0)?

My initialization string includes &D2, but that hasn't changed. I guess I can try that and see what happens. Thanks, Tim.

Could you post the init string?
Also, were the modem drivers updated? (Maybe automatically)
Was the comm software updated?

Sure. It is now ATE1Q0X1&C1&D2S8=13S11=200

Nothing has changed, no upgrades, no drivers. It's just for basic remote programming at 19.2K baud max.

&D2 will hang up the modem when DTR drops. &D0 causes modem to stay online regardless of DTR.
Also, the X commands only affect what is reported back from the modem, not what the modem does.
The &D2 command could be the problem here. I assume you use a similar string for the other (working ) modem?

Yes. I have the internal modem that is giving me problems, but I also have my Motorola Startac cell phone connected as an external modem using COM2. Note: There aren't any IRQ conflicts either.

The same initialization string using the same programs works fine on the external (cell) modem. It's the internal modem that seems like it doesn't want to play. I still can't understand why "AT&F" shouldn't solve my problem from a blank terminal screen.

I let the program initialize the modem using the aforementioned string, then I manually enter "AT&F". For all intensive purposes, that should have defaulted any of the changes my initialization string created, correct?

I use X1 to force the modem to NOT monitor for dial tone or busy when dialing out. Otherwise, I can't transfer a call INTO it or call into a system via auto attendant. It thinks that it has encountered a busy signal when it hears voice. I've been using that setting for years on all of my modems, both with this one and a half-dozen of them at the office.

I frequently have to dial into a system manually and navigate my way to a point where I can get to the system's modem. Once I reach the distant modem, I type in "ATD" from my terminal screen, transfer the call to my modem's extension, then hit enter. That has worked fine for me. Obviously, I can't use the "ATA" command, so I just let my modem "think" that it initiated the call and everyone is happy.

I've just tried &D, &D1 and &D2 (each time saving the entry using &W) and the same exact thing happens: It dials the number, pauses 13 seconds based upon my S8 setting, dials the remaining digits, then drops the call with a profound click.

Oh and yes, I do have the line cord connected to the proper jack on the modem card. Just in case, I tried it both ways!

Maybe I just have a bad modem card. I hate to part with it since it will work down to 300 baud for older systems; something that is hard to do with newer modems. I guess I can snag one from work and bring it home if necessary, but I just find it odd that the problem is so predictable every time.

Before you chuck the modem, issue an AT&V1 command after the link drop. The results should include "Termination Reason" or similarly worded thing. I'd love to know what's reported.

Yes, AT&F superceeds every command previously issued. But if there's any question about what setting is or isn't in effect, it's handy to know some of the ATI commands. ATI4=Return current modem settings and ATI5=Return NVRAM settings. It might be worth comparing these two option sets to see if they match.

Ofcourse there's also the option of uninstalling the comm software and then the modem from Device Manager. It HAS to happen in that order. Then re-install them in opposite order.

When I mentioned updates, I didn't mean updates you're aware of. Maybe the comm software auto-updated itself? Maybe another program updated/replaced the Windows serial driver? Maybe a new piece of hardware is responsible? Maybe the modem driver is set to "call home" and updated itself or/and the modem ".inf" (settings) file?

I don't mean to be nit-picking but I think the X1 command will make the modem to not report the non-existence of dial tone to the terminal, it does not tell it to disregard it.

If I recommend again to look at the modem "Properties" in the Device Manager as I mentioned previously. The Modem tab has an entry for Dial Control. That's another place to tell the modem not to wait for dial tone.
Then move to the Diagnostics tab and "Query" the modem. That's the equivalent of all AT&V and all ATI commands together. The very first line in that little window is the current init string for the modem. Also check "Append to Log", and then view the log.

Good luck!

Here's a cut/paste of what AT&V1 returned after a failed call attempt:

OK
atdt96586699,#499 (Call dropped immediately here after last digit was dialed)
NO CARRIER
at&v1
ACTIVE PROFILE:
E1 L3 M1 Q0 T V1 X1 &C1 &D1 &G0 &T0 &P0
S00:000 S01:000 S02:043 S03:013 S04:010 S05:008 S06:002 S07:001 S08:013
S10:014 S12:050 S16:000 S18:000 S29:070

STORED PROFILE 0:
E1 L3 M1 Q0 T V1 X1 &C1 &D1 &G0 &T0 &P0
S00:000 S02:043 S06:002 S07:001 S08:013 S10:014 S12:050 S18:000 S28:000
S29:070

ERROR

Oh, and to SPH: You are not nitpicking at all. Any suggestions that you have made are greatly appreciated.

I see that the AT&V1 reports the profile rather than the line conditions. This must be a US Robotics or other brand that doesn't use the Rockwell chipset. Exactly what brand is it? Issue an ATI7 command if you're unsure.

Regardless of the make, I'd say the S007 register value is way too low. Strap it to something like 60 (ATS7=60) before making another test call.

If your modem gives up again, send an ATS86? command and see if the Call Failure Code is reported there instead. The code will likely be a number rather than text.

I don't like that "ERROR" response at the end of the profile list; "OK" was expected. I'm not sure if that's important or not right now, but it's bugging me a bit.

S7, the wait for answer timer. That has to be it! I don't know how I missed that. I'm going to try it right now.

Yep, that was exactly what it was. S7 was set for one second. I still don't know how that happened, but who cares? It's working and I'm happy.

Thanks a million for your help everyone!

Very cool! I wouldn't have seen it unless you did the profile dump.

And I've got to hand it to sph, he was on top of the ATS86? query long before I was. Some modems are commanded by ATV0 or ATV1...others via the s86 register. What can I tell 'ya? I was impressed, so I gave him a rating.

The thing about the X1 parameter makes sense, especially if you're using a Lucent Technologies LT Win (Agere) modem. That modem in particular has a habit of detecting dialtone when conversation is on the line, which it proclaims after sensing a ½ second of audio energy on the line--regardless of the frequency or cadence.

Wow... I didn't think this would ever be figured out.... It does go to show that there is a great deal of arcane knowledge here, and it will be completely lost on the next generation....

I totally agree! :bow:

What a major learning experience this has been to follow this epic along. It just goes to show what a high level of knowledge there is here and the commitment to help one another across the country.

Mentors are you all, thanks for the lesson.

aww, i'm all bummed i missed this one... i did modem tech support back in the 90's until Dennis Hayes bought the company (after Paul Allen got done raping & pillaging us!).