mn :: comp :: net

Unix Modem Info

this was all written by Ramon Gandia, I am merely archiving it.

[headers snipped]
Dennis Veatch wrote:
> 
> I having problems with modems. It started out with an Amquest 56K internal and
> also happens with the USR 56K external. These problems occur in Windows98 and
> L-M 6.1.
> 
> Problem 1; The modem goes off hook, there is the dial tone, the number is
> dialed, the dial tone comes back. Sometimes the modem resets itself, most times
> not. I have verified the modem settings that are software related and used a
> terminal program to verify individually the settings of the modem profiles and
> S registers, all are at factory defaults.

This is an indication of a bad phone line or a defective modem. It means that your modem is not putting enough of a load on the phone company switch to hold the voltage below a certain threshold (at the phone company). This could happen, for instance, in the modem if it had a bad relay (switch contact, the thingy that goes click inside), or in the phone line if there are bad/rusty/high resistance connection.

With house wiring, it could well affect the wiring going the the jack in the computer room but not elsewhere in the house.

Most phone companies provide an outdoor box with a modular test jack. When the box is opened with a wrench, there is a swingout protector that disconnects the house's wiring and exposes a conventional modular plug for that line. You can plug in a regular phone cord there for testing. Get yourself a brand new 50 or 100 ft phone cord and run it thru a window to your modem and see if the problem disappears.

However your dial tone irregularity indicates a phone line problem or a defect in the modem itself. In modems I have seen those after surges like a powerline falling across phone wires, or lightning strikes. These can happen miles from your house and can fry wiring, modems, etc.

You can borrow a modem from someone to eliminate the possibility of a bad modem. If the problem persists with the new modem, then you use the long cord to eliminate the possibility of a bad house wiring. If you have two phone lines in the house (two separate numbers), try temporarily using the ohter line and see if the problem goes away. If you determine it is at the phone company's, a call is in order.

In Alaska, lightning is rare, but is very common out there. You get a lightning strike a few miles away. The spike travels on the phone wire and fries your modem, indoor wiring or the phone company wiring or outdoors protector on your house. If the failure is not total, you get intermittent problems like you are reporting.

Another thing to check is your login procedure. Your successful log in indicates that you are using a Script. Many ISP's, myself included, do not require a script and in fact will reject your call after authentication. Just hang up on you after verifying username and password. This is a function of several things at the ISP, and different terminal servers can behave differently. Thus one call may succeed, while others do not. This is because when you dial the ISP's phone number the call may at random be assigned to different terminal servers.

If in Windows 98 you do not need a Script file or a Terminal Screen, then how come you are using one in Linux?

The fact that the ISP requested a hangup or termination seems to me to indicate that this is the problem.

Also, be careful who you talk to at the ISP. ISP's are flooded by tech support calls. Ask me: I am an ISP and I can tell you that clueless users can take up a lot of time. We get calls blaming Nook Net for being out of service, and the message on their screen is "No Dial Tone". Really.

What this means is that ISP's tend to employ minimum-wage young techno-geeks in their support department. This is an entry level position. It is a tedious job relating mostly to real_dumb questions. Most of these kids are really not electronic technicians nor are they versed at all in the workings of their Terminal Servers, modems, etc. The fact that the kid that spoke to you told you that your USR External modem used a Rockwell Chipset is an indication that he is clueless himself and he is just posturing as an expert when in fact he is a dumbkopf himself.

What you need to do is to get past this first layer of ISP technical support and see if you can speak to the head honcho over there. Most ISP's, like myself, have literally seen -and fixed- everything you can imagine. I am not down there to help you, and some of the troubleshooting that you may need can only be provided on-site or by interactively asking questions.

Both Linux client machines and Windows 98/95 have different tools and procedures which can answer some of the questions. The PPP logfile of Linux is unique; but there are corresponding log files at the ISP and at your Windows 98 box. Any or all of these may provide clues as to what is wrong, as will long phone cords, voltmeters, desk telephone sets and spare modems. A good ISP that actually provides technical support is armed with all of these tools.

For instance in recalcitrant cases I go to the customer house with my laptop. It runs Windows 95, and has a PCMCIA modem that I know works very well. I can plop it down next to the customer computer and fire up using HIS login and password and demonstrate to him tht his phone connection and Nook Net is fine, and that the problem is inside his computer. As an example.

Or, I could also have trouble, in which case it could be a phone line. Lastly, assuming the problem is in his computer, I can use my external USR 56K (the most bulletproof modem I know!) and show him he has a poor modem. Rockwell WinModems are really, really bad. the new .160 and later drivers for them make them barely acceptable. The Lucent LT WinModem with the new 566 driver seems to do well too, but earlier versions have lots of problems. Poor thruput regardless of reported speed with WinModems is endemic. A new driver can sometimes help. It takes a Pentium 166 minimum to handle a WinModem. Less than that, the WinModem is paused every time the mouse cursor needs to move or the disk drive is accessed. WinModems, as a rule, do not handle poor line conditions. They disconnect, or spend all their time in retraining and changing speeds and do not handle data for 15 or more seconds at a time. Then they resume for a while, and then again the same thing. Very bad. And the Rockwells are the worse. Actually, the Cirrus Logic are the worse, but they are discontinued and never were very popular. Alas, all new computers come with WinModems and most are Rockwells.

Try and tell an owner his brand new Hewlett Packard $1,500 computer has a piece of shit modem and see what happens. With some customers, what I do is LOAN them the USR external 56K for a week or so, and after they use it a week their eyes are opened and understanding settles in their souls and they spring for a better modem - after consulting with me first so they do not get another piece of junk. Or, they can buy the one I left there. In most cases, that is what happens and I get to sell a USR external 56K Sportster at List price. :-)

You already have the best modem made, for all practical purposes. Most modems, the big thing is the Chipset. Alas, most externals come with Diamonds.

How can you tell, here is the clue:

1. On a 33.6K connection, V34 analog, all sound the same.
2. On a Rockwell, when you dial out and the modems connect, yhou will hear first the Eeeeeh-Ohhhh, Eeeeeh-Ohhhh of the 33.6K initial connection. If you hear more than one repetition of this double eeeeh-ohhh, it means that you are retraining for a lower speed. Bad.
3. Then there is much hissing, now comes the important part.
1. The rockwells will growl like a dog, followed by a beep and you get silence and you are in.
2. The Lucent will go click click click click like a ratchet being turned, then the beep and then silence.
3. The USR/3Com/TI will go Booooong....Boooooong like Big Ben in the fog. Then the beep and silence.

Of course, these noises can change depending on what the ISP has at his end. But its a starting point.

At the ISP end, you can have USR, Rockewell or Lucent equipment. I have Lucent. No one could make the Rockwell work here (Cisco, Ascend), but the Lucent Portmaster works well. Like I said, Rockwell really does not have their shit together.

A lot depends on intervening Telco equipment.

4. If the noises are no clue, in Windows 95 go to Control Panel, Modems. There you will see your modems listed. Go to Diagnostics. In Diagnostics highlight the appropiate COM port, then hit more info. That sends the modem a series of ATI commands. ATI3 and ATI4 will reveal the modem type. Usually you will see things like Rockwell HCF or Rockwell HSP. Or there is no clue but you will see version numbers with embedded digits like .538. Basically embedded digits in the .100-.200 range are Rockwell, and digits in the 400-600 range are Lucent. Robotics and TI will state so.

Some of this information is not appropiate to your problem, but as long as was giving a speech here on the list I thought that I would spiel out the propaganda.

You can find the final authoritative answer as to which modem is WinModem or not, along with a host of data on ALL and EVERY modem ever made, at http://www.o2.net/~gromitkc/winmodem.html this is the final authority on modems and should be a bookmark for everyone on this list that has a modem, or will ever help a friend with a modem.

Good luck!

OK, here is the technical lowdown.

1. Serial Port. This can be the built in port, which goes to a 9-pin or 25-pin socket in the back of the computer. OR, it can be an identical port in the modem, the only difference being that on the modem it goes on to the innards of the modem rather than to the socket in back. This is true of conventional modems; on a WinModem the "serial port" is "simulated."
2. Modems. Modems can have many settings. Not all modems are created equal. There is a "command set" that can set various parameters. These commands are known as the "AT" command set, because when you send a modem an AT command, it will respond.

   An example is ATI3. Or, AT and then I3. This command, as well as other Ix commands make the modem give out some information. Usually there are commands from ATI0 thru ATI13 or more.

3. AT commands are not the same for all modems. The AT command set was loosely defined by Hayes some years ago, but MOST of the commands in use today are not in the original Hayes set. The outcome is that while some commands are the same for all modems, most are NOT.
4. Usually the commands that have no fancy signs are the same. Thus, Ix at least for low numbers such as ATI3, are the same for all modems. I think up to I5 was Hayes, the rest is whatever the particular modem company wants. ATH = Hangup, ATZ = reset.
5. Punctuation commands, like AT&F1, AT&C2 (note the & sign) or anything with %, # and so on are proprietary.
6. On a WinModem, anything goes. Most AT commands are ignored by winModems. ON conventional modems there are so many permutations... For instance, to initialize a modem to factory conditions may require this command: AT&F or AT&F1 but may be different. This resets the init string from the F register or the F1 register. There may be many such registers. In the US Robotics Couriers I have here you can go to F4. These are "preconfigured factory configurations."

   On the sporster and the courier, you want F1 settings as they are most appropiate to Internet use. For data transfer by way of the old BBS or XMODEM or YMODEM protocols etc., other settings may be more appropiate. Perhaps F2 or F3 etc. I would not know. You can concatenate commands. For instance, to tell the modem to be silent, you set the volume to zero. This the Mx command, M0. Just plain M with no number will in some modems reset the volume to factory default. The following is a valid USR command:

   
   	AT&F1M3
   
   

   this says: Restore the factory F1 register set for internet use, except once that is done, I want you to do M3 to set the volume to the highest setting. Note the Sporster external ahs a volume knob on the side. The M0 thru M3 set the internal volume level, but the knob sets the actual maximum volume. If you have the knob all the way down you will not hear a thing regardless of the M3 setting.

7. Windows 95 and 98 have collected (or the manufacturers have supplied) a plethora of initial commands that make their modems work well on the internet and have defaults deemed appropiate by the manufacturer. For instance, the default may be "best internet" and "low volume".

   This database is not available to Linux users. Jack here -- Interested readers might have a look at http://freshmeat.net/projects/initinf/ -- I haven't tried it, but it looks like it's a step in the right direction.

   The default factory configuration may, or may not be appropiate to Internet use. In the vast majority of 14.4K modems this was the case. Nowadays, most modems have decent power-on defaults, unless you change them and save them to an internal user register. Usually with the W command. W1 to internal register W1. You can then recall this with some AT command. Normally, this is not done inside the modem anymore. Usually both Windows and Linux will RESET the modem, then send it an init string, like "restore factory configuration" but "change the following parameters". This means the modem starts from a known state and proceeds from there.

   In Linux, since there is no modem database, the results can be less than optimal. The US Robotics Sporster External data/fax 56K like you have coming, will power up to factory defaults which are fine for internet use. Note it will not come up on the factory register, but user register #1, which has been set to be the same as factory register #1. If you want the factory settings to be ensured, the init string should be AT&F1.

   However, if nothing disturbs the modem settings, then just ATZ (reset) will work. But this assumption is seldom valid.

   Minicom, for instance, will usually give a modem an AT string that sets it up for terminal use, but is terrible for internet use. If the setting is recorded in the modem, then it will reset to the minicom value. This is bad for PPP.

8. There IS a setting in SOME modems for maximum telco line speed. There IS a setting in SOME modems for minimum telco line speed.

   Why would you use that? Let us say you are dialing in to a weather station with an old, fixed speed modem of 1,200 baud. If you use the wrong protocol, or the wrong speed, the weather modem goes bananas and dumpss you. It is an old modem and works at a fixed speed, and has no intelligence or the capability to change speeds or follow along with the other modem. So you would set your own modem to have a Max and Min speed of 1,200 locking it in. YOu may have to set other parameters as well, such a number of bits, parity and so on; and perhaps the modulation type such as V32BIS.

   Both Linux and Windows give you this capability IF YOUR MODEM SUPPORTS IT. Many modems do not. The Sporster has limited capability in this regard, the Courier has much more. IN the example I jsut gave, both will do well. Other brands may not.

   For instance, in the BOCA modem I have here, the AT commands fit in a page and a half. No speed settings are possible. And the majority of the AT commands are weird to boot.

9. Another possibility is you do not want to use the modem thru the phone system. You may want to transmit via just two plain wires (a single pair). this may be useful on a factory or a campus, but you can also rent wire pairs from the phone company. No dial tone or anything; its just a wire pair from your house to some factory somewhere. Range is usually limited to 4 to 8 miles depending on speed. Most modems NEED a dial tone or they go nuts or do not work. Some can handle "leased lines" For instance, the USR Couriers and some of the Multitechs, and all the Motorola commercial grade modems support this feature. Most top out at 14.4K in this mode, but a few, liek the USR and MUltitech will do 28.8 or 33.6K on a wire pair.

   Usage on wire pairs requires a creative set of AT commands to prepare the modem, or it will complain and fail when it is asked to connect and finds no dial tone.

   For this mode to work the AT comands are totally different for different brands of modems. I have some motorolas here, and the commands to do so do something unrelated in the USR Courier. Like I said, except for some simplistic commands from the 1970's, the AT command set is as defined by the particular modem manufacturer.

10. You have to pay attention to semanthics, and what each programmer means. Something that means one thing to you, may mean the opposite to a programmer or manufacturer. This is particularly true of one-word names etc. For instance "Connect Speed" setting could mean "Connection Speed MODEM to PHONE LINE" to one person, or mean "Connection Speed MODEM to SERIAL PORT" to someone else. Bummer. IN fact, U.S. Robotics is not clear in their manuals either. You think you know what they mean in the manual, but you are only 85% confident that you have it right. This is very frustrating. For instance, there are DCE and DTE devices.

    Normally the modem is a DCE device, and the TERMINAL it attaches to is a DTE device. But when you say: "DTE speed" are you referring to the Speed on the modem serial port that communciates to the DTE device on the end of the cable, or are you referring to the Speed of the Computer serial port which is the DTE device?

    These semantics can create all sort of ambiguities. The funny part is that most programmers and manufacturers are clueless.

    Example. You go to work for US Robotics. You learn the jargon, you learn the way they do things. To you, DCE means this. Anything else is "wrong" to you and you do not conceive of any other way of doing it or naming it.

    But your buddy, he went to work for Motorola UDS division, and he learned a jargon that has IDENTICAL names, but different meanings. To him, the Connect Speed may mean something different. Who is wrong, and who is right?

    There is no right way and no wrong way. You need to be savvy enough to catch on, or savvy enough to ask exactly what they mean.

    I wish I could tell you that "Connection Speed" according to KPPP means Serial Port speed. I think it does, but I cannot guarantee it. Why? Because I do not use KPPP. IN fact, NONE of my LInux boxes here has a modem on it, they all use ethernet. I set up a Mandrake 5.3 box for my secretary Sara for use at home, but I will be darned if I remember any of this, and I am not about to go over there and face Cigarette Smoke and Cats all over again. Hehehehe.

    So, you are on your own on this one. And, once you learn the answer, it is probably "trivia" because Mandrake 7.0 is out. I think it uses KDE 2.0 and KPPP probably been rewritten and most likely, being GPL, the guy that did the rewriting went ahead and changed the meaning of it. Possible? Yes. Probable? Yes too.

    Now, I was writing KPPP, I would call the setting not "Connect Speed", but "Modem's Serial Port Speed Modem to Computer." That is very specific and obvious, as compared to "Computer Serial Port Speed, Computer to Modem."

11. To confuse the issue, most serial ports are "Auto Sensing", so if the Computer is autosensing, and the modem is set to 115.2K, you get a 115.2K link. I can assure you that this is NOT A GIVEN. For instance, with the Multitech ZDXb unit, you can set things to 115.2K all day long and end up with a 57.6K serial cable link. this is because both ends are autosensing and the Multitech then says:"Gee Whiz, one of us has to go first, so I will try 57.6K and see what happens." A few seconds later the two communicate, so the modem says "Gee, 57.6 worked, I better stay here." INfact, there are a LOT of modems that will come up on 57.6K and not on 115.2K. YOu have to be careful because using 57.6K on a 33.6K or 56K modem will have terrible effect on thruput. How do you fix the problem? You do it with the proper AT command to the modem to tell it to start at 115.2K. It then will work okay if the computer is autosensing. But beats me what the AT command is, and it will be different for different brands.

    windows 95/98 has this ALL FIGURED out in the .INF files that reside in C:\WINDOWS\INF (a hidden directory but you can CD there). There you will see hundreds of MDM*.INF files pertaining to modems, and each one has had its quirks figured out for Windows 95/98 and it will come up with the best settings.

    With Linux....well, you have to figure this out on your own. This is one of the reasons that Linux, in 90% of instances will transfer PPP slower than windows. There are all sorts of nuances to this. A lot of it requires proprietary manufacturer info. In fact, not so much proprietary, but simply that no one asked the manufacturer for the details, and no one has written a KPPP or other PPP daemon that has such a database.

    I think that it would be fairly easy to write such a PPP or KPPP program that could use the INF files from Windows 98. Its a bunch of text files, after all. The problem here is that they are probably copyright by Microsoft or the Modem maker and you cannot distribute them. However, I suppose that the PPP program can be Linux distributed with the instructions to "Take a Win95 or Win98 cd and copy over all the MDM*.INF files".

    I should mention that the INF files are basically unreadable by humans. They are text, but go try and figure things out.

What I have found that works is to set your modem properties so you write a modem log, C:\MODEM.LOG as I recall, and make your connection to the Internet via Windows 95/98. Then log out. If the connection was satisfactory, you can then look at the modem.log file and see exactly what AT commands were sent to the modem by Windows 98. These are probably exactly what you want for your Linux box. Take these commands and plug them in by manually editing the pppd dialog files.

This is all kinda tedious for us Linux users, but it is all part of the fight against the Evil Empire and their machinations and attempts at world domination.

-- 
Ramon Gandia ============= Sysadmin ============== Nook Net
http://www.nook.net                            rfg@nook.net
285 West First Avenue                     tel. 907-443-7575
P.O. Box 970                              fax. 907-443-2487
Nome, Alaska 99762-0970 ==== Alaska Toll Free. 888-443-7525

Last modified: Oct 24, 2008 2:28 pm. Contact me.