The modem is a difficult device which serves for digital data transmission. If the modem analog, it transforms an original digital signal to analog impulses, and then the special modulator will change their characteristics – frequencies, amplitudes and phases.
That information reached the user, analog impulses pass through the demodulator which turn into an original digital signal. There are different types of modems performing a set of functions. These devices are internal and external. The internal analog modem is located in the computer case and is connected directly to the motherboard. The external modem is a separate device which is connected to the serial or parallel port and is powered from an electrical network.
Modems work under special protocols of communication which are divided into several groups. Each of groups is responsible for certain parameters. For example, the first - accepts an analog signal and controls its coding. The second - checks the coded signal for existence of errors and if they are available - requests its repeated transfer or issues the report on an error. In both cases the device will be switched-off and will report the error number or request for repeated connection.
The third group of protocols is responsible for the organization of connection and data exchange between RAM of the computer and the modem – she gives certain rules, commands. Knowing coding of the transferred errors, it is possible to understand the reason of shutdowns. If you connect the new device leave configurations by default or enter settings which are described in the manual.
If at connection attempt there are periodic errors, they can be checked by means of standard commands. For example, the modem the error does not dial number: "There is no line signal", check a command on the X3(X0) keyboard. Keep in mind, the way is useful, only if the device is connected and is in working order - the long beep is heard, but the selection signal is ignored.
You made sure of serviceability of the modem, but it was switched-off before data exchange - it could be the result of very silent or very short signal of automatic telephone exchange. Try to make X2 team. Keep in mind if the device has no necessary sensitivity, then, function will not help.
Happens so that the modem is switched-off during check of a user name and the computer. Look at value of the installed interval of the waiting configured for this connection - it, most likely, too short. To change value, open "My computer", "Remote access", click the right mouse button on an icon of connection and select the Properties item find the Setup button In the opened menu and select the Connection tab. Change numerical value opposite to a line "Canceling of a call in the absence of communication" or remove this checkbox.
The bad quality of the line, existence of noises, periodic signal attenuation, restricted speed of data transmission can be the cause of breaks of communication. Errors of connection are eliminated by installation of necessary settings which approach according to the manual the specific modem.