3Com 3CXM756CA Megahertz Global GSM and Cellular Modem

3COM Part #/MPN: 3CXM756CA

DiscTech Item #: 3CO-3CXM756CA-BN-OE

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3Com 3CXM756CA Megahertz Global GSM and Cellular Modem PC Card w/XJAC for Canada - Brand New

  • Fast V.90 56K downloads
  • DOS, Windows, MAC, Linux
  • GSM and Cellular
  • Global Connections

Modem Features

AT Command Help Screens

AT commands allow you to control many of the functions of your modem. You can use AT commands by typing them at the command line of any Terminal program.

Your modem can display screens summarizing AT commands (AT$ and AT&$), dial command options (ATD$), and S-Register functions (ATS$).

Automatic Cable Sensor

3Com's analog cellular cables allow your modem to recognize the cellular telephone to which it is connected automatically.

Automatic Calling Card Dialing

Whenever you make a calling card call, your modem will detect the tone that sounds prior to entering your calling card number. You can have the modem automatically enter your calling card number and place the call by entering the following string:

    ATDT <phone#>&<calling card#>

Call Progress Detection

An optional set of result codes lets you know when:

  • The telephone number you have dialed is busy
  • The line has been picked up, but a modem is not answering the call
  • There is no dial tone on the telephone line
  • A call is coming in

These result codes, and the commands that enable or disable these result codes, are controlled by the ATXn command.

Caller ID

If you live in North America, your modem allows you to identify callers' names and telephone numbers when they call. Your communications software must support this feature, and you must subscribe to Caller ID from your phone company.

Use AT#CID=1 to manually turn on Caller ID and set S=2, because Caller ID is received between the first and second rings.

Analog Cellular Communications

With the purchase of a cellular upgrade kit, you can connect your modem to a cellular telephone to send and receive data and faxes.

Dialing Stored Phone Numbers

Your modem can store up to four of your most frequently called numbers.

For example, suppose you are dialing a phone number of 123-4567, and it is the first number you have stored. You would enter AT&Z0=1234567 to store the number, and ATDS0 to dial it. To dial the second phone number in the stored numbers list, you would enter AT&Z1=9876543 to store it, and ATDS1 to dial it.

Digital Line Guard

For landline connections, protects the card circuitry from overvoltage from ISDN or digital PBX lines.

Exclusive Line Probing

Exclusive Line Probing technology for V.90 connections automatically steers you around even the worst line impairments, allowing faster connections and transfers.

Flash ROM

The firmware in your PC Card can often be updated to correct problems without returning your card to 3Com. This capability is called "flash ROM." Current flash ROM programs and the instructions to use them are on the BBS and the 3Com Web site.

If your modem is functioning properly, there is usually no need to flash it. In any case, we recommend flashing it only under the direction of a Customer Support Application Engineer.

GSM Communications

You can connect your computer to a mobile telephone and use the GSM system to send and receive data and faxes.

Redialing the Last Dialed Number

Your modem stores each dialed number until another number is dialed. Enter ATDL to redial the last number dialed during the current session.


With communications software that supports Speakerphone functions in Windows 2000, 98, 95, 3.1x, and NT 4.0, you can use your computer as you would a telephone if your computer is equipped with a sound card, a speaker, and a microphone (either built-in or externally attached), and a multimedia subsystem is installed. Use your modem to dial the number, then use your computer's speaker and microphone to listen and to talk. Refer to your communications software manual for instructions.

Telephone Answering Device (TAD)

Your modem, when used with communications software that supports this feature, allows you to send and receive personal voice mail. If you have a multimedia computer, you can send greetings and record voice mesages as you would with a standard answering machine. You can even access your voice messages remotely.

Your software and modem can autodetect incoming fax, voice, or data calls and provide fax-on-demand services that you can tailor to your needs.

Many communications software packages support voice messaging. Refer to your communications software help files or manual for details about using this feature.


With V.90, your modem will be able to download (receive) data files at up to 56,000 bps. Uploads travel at V.34+ speeds. A V.90-compatible local analog phone line and V.90-capable service provider are required for these high-speed downloads and uploads.



NOTE: Capable of receiving at up to 56 Kbps and sending at up to 31.2 Kbps. Actual download speeds you experience may be lower due to varying line conditions. Requires compatible phone line and server equipment. Complies with both the V.90 56K standard and x2 technology protocol.

WorldPort Country Select Software

WorldPort Country Select software allows you to select the country where you plan to use your modem, and automatically configures the modem for that country's telephone system to ensure compatibility and high performance.

If you travel to a different country, you can change your modem's configuration by doing the following:

  • Open WorldPort by clicking its icon or, if you are using Windows 98 or 95, go to Start>Programs>3Com Utilities>WorldPort to change countries.
  • If you are using Windows 3.1x, select WorldPort from the 3Com Utilities program group.
  • If you are in a country that is not listed, select USA.

Connecting in different countries may require trial and error until you determine exactly what you need, because a particular country may have multiple exchange systems that require different configurations. The information provided below is to help you with this process.

Be sure to have the correct country adapter when you try to connect. We suggest you try each step below, one at a time, starting with number 1:

  1. In the WorldPort Country Select Software, locate the country you are connecting from, select it, click OK, and try connecting.
  2. Set the WorldPort Country Select Software to USA, try setting blind dialing, and try connecting.
  3. Try blind dialing. Not all countries use the same signal frequencies to generate a dial tone. This difference can lead to an issue where the modem appears to work fine in one country and not in another country, generating a "No Dial Tone" warning. Also, some analog PBX systems generate a silent dial tone that your modem cannot detect. With blind dialing, you can dial regardless of whether the modem detects a dial tone or not.

Blind Dialing

Blind dialing lets you dial regardless of whether the modem detects a dial tone. Turn on blind dialing by inserting X3 into your software initialization string immediately before the telephone number. This setting disables any "Detect Dial Tone" feature in your communications software.

If you are using Windows 95 dial-up networking, follow these steps to turn on blind dialing:

  1. From the Start menu select Settings>Control Panel.
  2. Double click the Modems icon.
  3. Highlight the Megahertz International Modem and select properties.
  4. Select the Connection tab.
  5. Under Call Preferences, deselect Wait for Dial Tone Before Dialing.
  6. Click OK.
  7. Click Close.
  8. Close the Control Panel.

To turn blind dialing off, issue X4 in the initialization string immediately after the telephone number or issue AT&Fn or ATZn.

Weight: 2 lb

Warranty: 1 Year DiscTech

Brand New

Condition Levels Explained

The product is brand new.

1 Year DiscTech Warranty

Product Warranties Explained

The product has a DiscTech warranty for the time period specified. View our limited warranty