Some modems are more dependent on your processor speed than others. These modems are called Winmodems. Often these modems have trouble receiving data sent to them. Please perform the below options to ensure optimum performance:
First, right click the My Computer icon and select properties.
Next, click on the Device Manager Tab.
Next, click on the + sign next to your modem. Highlight your modem, right click and select properties.
Under the modem tab the default Maximum Speed setting is at 115,200. Set this speed to 57,600.
Next, click on the advanced tab. Under the advanced tab click on advanced port settings under the Connection tab click on Port Settings.
The last thing you will want to do is to set the receive buffer and transmit buffer options to their lowest settings to ensure best connectivity.
Please also be sure to have the latest drivers for your modem installed.