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Communications
You need a device called a modem to connect to the Internet from your computer over the conventional telephone system.
The word MODEM comes [MOdulator] DEModulator. Modems can dial the number of another computer or a central computer, reply or make a call to transmit data and then hang up. When data is transmitted from your computer, the modem converts the data into a form that can be transmitted over the telephone line. When your computer is receiving data, the modem also converts the signals that come in so that they can be understood by your computer.
There are two basic types of modem: internal and external.
An internal modem is a card that consists of various circuits and chips. The card is inserted into an "expansion slot" inside the computer. The modem must be connected using a telephone cable that comes out through a hole in the back of the computer. The telephone cable is connected directly to the telephone socket.
A normal external modem is a small box, often about the size of a pocket book.
The external modem is connected to the computer via a "serial" cable connected to a "serial or COM port". Normally they need to be plugged into the mains electricity to work.
Generically, a port is a point where devices are connected. In the case of computers, the ports are interfaces where peripherals like the mouse, printer, modem, etc. are connected. Computers normally have two serial ports (known as COM1 and COM2), which is where the modem is normally connected.
Most modems have an external microphone so that you can hear the modem. If the modem does not dial and messages like "Cannot initialise the modem" appear on the screen, check the following points:
- Is the modem switched on and receiving power? For external modems: there should be at least one light lit up (e.g., the MR or S light) if the modem is connected and receiving power.
- Is it correctly plugged into the telephone line? Modem have both a line connector and a connector for a telephone. Connect the cable (usually from a wall plug) to the line connector on the modem. Then connect a telephone to the telephone connector on the modem. Pick up the telephone receiver. If (and only if) you hear a dial tone, the telephone line is properly connected.
- Is the serial cable connected properly? (only external modems). Generally, the cable has 25 pins for connecting to the modem and 9 for connecting to the serial port on the computer. Make sure that this cable is correctly connected. Use another serial cable to check that the first cable is not faulty.
- Is another communications program (e.g., a fax program) operating? If another program is using the modem, you will not be able to connect to the Internet. Close the program that is interfering and check again.
- What port is the modem connected to? The modem port can be configured as COM1, COM2, COM3 or COM4. Use the option "Modems"in the operating system "Control Panel" to check and/or configure the port for your modem.
It is always necessary for you to connect to the Internet over a basic telephone line. There are other options for Internet access that are faster and more modern, like ADSL and IDSN.
This is the way that the modem is going to dial the telephone number that it calls to get the desired service. In 99% of cases, we should select TONE dialling (multifrequency sounds) but if your installation is very old you will need PULSE dialling. IMPORTANT: If you select PULSES, the communication will take place correctly, even if your line permits TONE dialling, but the dialling time will be longer.
It is the Integrated Services Digital Network, which integrates a multitude of services, such as voice or data, into one user access that permits high-speed digital communications between the terminals connected to it (telephone, fax, computer, etc).
ISDN uses the user's existing infrastructure. When you ask for a Basic Access line, your telephone provider will install a network or TR1device, like a small box, with two RJ-45 connectors so that you can directly connect your ISDN terminals.
ADSL (Asymmetrical Digital Subscriber Line) is a modern technology that transforms TRADITIONAL telephone lines into high speed, permanently connected lines. ADSL provides high speed Internet access as well as access to corporate networks for telecommuting and on-line multimedia applications like on-line games, video on demand, videoconferencing, voice over IP, etc.
It is important to note that in Spain the ADSL technology has three independent channels on the one telephone line:
- Two high speed channels (one to receive data and the other to send it)
- One channel for normal voice communications, modem, fax, etc..
You should bear in mind that this service is intended for Internet connections, and that the PC in which it is installed must have a processor that is superior to a PENTIUM 233. It should also have an Ethernet network card installed for it to work properly.
When you contract an ADSL line. you can have various services. The installer will also configure an ADSL device, connected to the data socket, that will allow you to connect to the Internet from the PC that is connected to this service, or from any PC on the office network, if the PC is connected to the network HUB of your office.
The voice socket is left free so that you. can install a traditional telephone or fax.
WinSuite32 allows you to select permanent connection or telephone access, depending on how you connect to the Internet. The instructions for this configuration are in the Users Installation Manual, which you will find in the documentation section of the RED System web site. You can also request it from the USU in your province.
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