Difference between revisions of "Modems"

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==Why  does my 56k modem always connect below 56k? ==
==Why  does my 56k modem always connect below 56k? ==
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Revision as of 20:37, 25 February 2008


Why does my 56k modem always connect below 56k?

Many factors influence your connection speed. Because modems use audible tones to communicate over analog voice telephone lines, they are very susceptible to phone line quality impairments. Such problems can make it difficult for the modems to hear the tones they are generating. These problems can exist anywhere along the path of your phone connection; in your home or office's wiring, at the phone company's central office and beyond. Your modem will try to negotiate the most reliable speed to connect at.

Is there anything I can do to speed up my modem?

While it might be possible to force a faster connection, it would actually end up slowing down your data. When the data your modem is sending and receiving become corrupted by line problems, it will re-send the data again until it comes through correctly. By forcing a faster speed you are actually only increasing the likelihood that your data will become corrupted and have to be sent again. Your modem connects more slowly in an attempt to protect the integrity of your data. Forcing faster connection rates is not advisable.

Why am I frequently getting disconnected?

Many of the variables in line quality discussed previously can also result in losing your modem connection. If this happens consistently you might be able to stabilize your connection by forcing your modem to a slightly lower speed than what it is attempting to connect at. You can limit your modem's connection rate with a modem initialization string. Initialization strings are a series of commands passed to your modem just before it dials (see below for details).

How can I improve the quality of my connection?

First, make sure your modem has the latest software drivers and firmware. Drivers are the software handlers that your computer's operating system uses to control the modem. Firmware is program code that resides on the modem itself. Check with your modem's manufacturer to see if they have newer versions of drivers and firmware than what you're currently running. You'll probably want to talk to your modem manufacturer's technical support to see how they recommend you go about the upgrade.

You can also contact your phone company to have your lines tested. In some cases your phone company may find line problems that they can fix. Be aware that you may be charged a fee for this service.

Why do I have problems, even though the phone company tested my line and said it's fine?

Be aware that analog telephone lines were designed to move voice, not data. In some cases the lines will test okay for voice but still not yield higher speed data communications. Many high speed digital options are available if your analog modem speeds can not be improved. Technologies such as ISDN and DSL may be available from your phone company and in most cases are compatible with your existing XMission account.

How can I modify or add to my modem initialization string under Windows 95/98/ME?

Click Start, go to Settings, and select Control Panel. From here, double-click the Modems icon, select your modem, and click Properties. On the Connections tab, click on Advanced, and enter your init. string in the field labeled Extra settings.

What initialization string commands should I use to limit my connection speed?

The best way to determine which init. string to use is to check your modem's documentation, contact the modem's manufacturer, or see what you can find on the web. In most cases you'll want to start the initialization string with the command &F followed immediately by the specific commands you want to use. Here are a few suggestions for some of the more popular modems:

US Robotics Courier, Sportster, and other "TI chipset" Modems:

The TI chipset uses &Nx to limit the maximum connect rate where "x" is one of the following:

x=11 21600 bps
x=12 24000 bps
x=13 26400 bps
x=14 28800 bps
x=15 31200 bps
x=16 33600 bps
x=17 33333 BPS
x=18 37333 BPS
x=19 41333 BPS
x=20 42666 BPS
x=21 44000 BPS
x=22 45333 BPS
x=23 46666 BPS
x=24 48000 BPS

Example: If you wanted to limit your US Robotics modem to 26400 BPS you'd enter an initialization string of: AT&F&N13

Rockwell-Based 28.8k & 33.6k Modems: Generally the +MS command is used to control modulation and connection rates. For example, adding a +ms=11,1,2400,26400 will limit the upper connect rate to 26400.

AT&T-Based Modems It seems as though the AT&T chipset is not as flexible as the Rockwell & TI chipsets. You can use S37=x to force a certain connect rate. That does not set a maximum or minimum connect rate, but forces a connect rate. "x" is one of the following:

14 = 21600 BPS
15 = 24000 BPS
16 = 26400 BPS
17 = 28800 BPS
18 = 31200 BPS

(Warning: Do not force a connect rate that is higher than your normal connect rate. When your modem makes an initial connection, it will determine that the lines cannot handle that speed, and immediately hang up.)

What other commands can I use in my initialization string?

The commands vary greatly between modems from different manufacturers. Consult your modem's documentation. You might also find these on-line resources useful:

What brand of modems does XMission use?

For digital connections, XMission uses US Robotics Total Control modem racks. They support analog-digital connections (x2/v.90/56k) and pure digital connections (ISDN 64k+).

Will XMission be supporting V.92 and V.44?

Not at this time. Subscriber interest for these features has not yet been high enough to cover the expense of upgrading our dial-up equipment. Technical forums have also suggested less than full compatibility across all modem manufacturers, and we would like to wait at least until these new features are standard across the industry.