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Cannot connect at 56K with my 56K modem

Background

Anything that adds noise to the telephone line or causes an analog-to-digital conversion between your modem and your Internet connection through us adversely affects the modem performance. For 56K to work, you can have at most one analog-to-digital conversion between your home or office and the Internet service provider. If there's more than one, you can't use 56K, and your connection will be limited to V.34 speeds (a maximum of 33.6K).

Digital lines usually don't suffer from noise problems, but the analog wires between the phone company's central office and your home are a different story. If you hear buzzing or static when you listen through your phone's headset, chances are you won't be able to achieve optimum modem speed. Caller ID, answering machines and cordless phones can add even more noise to your line. To minimize the hum try disconnecting these types of devices one by one and listening again to determine which, if any, are the source of the problem. If this doesn't work, your line noise may be caused by nearby power lines or other environmental or structural factors. Central office switch-up Connections between local central-office switches can sometimes be a problem. Old equipment may require analog termination, resulting in an analog-to-digital conversion as the call goes through to the next switch. If a local call to your Internet connection gets routed through these "partially analog" switches, you'll lose 56k capability.

Though your modem says it's "56k," you won't get throughput that fast, thanks to a speed limit set by the FCC (Federal Communications Commission). Sending a signal down a telephone wire requires electrical power. But the more power you apply, the greater the chance of a problem called crosstalk (when you hear other people's conversation during a phone call). To help prevent crosstalk, the FCC limits the amount of power that phone companies can use to send signals over the network. And this cap on signal strength limits data throughput to a maximum of 53 kbps, regardless of what your modem can actually deliver.

If you have to dial 9 to get an outside line, your office uses a digital PBX telephone system, which means you also won't be able to achieve 56k rates. A PBX system incorporates a codec that performs an analog-to-digital conversion so that your calls can be stored digitally on magnetic media, such as hard disks. Though this system gives you some great features, such as employee extensions and call forwarding, it also limits your 56k calls to a maximum throughput of about 35 kbps.

There may also be a "pad" between you and the central office. A pad balances the volume on both ends of the line when you make a call. If the pad occurs before the signal is converted to analog, you'll see only a slight degradation in 56k performance. But if you encounter an analog pad between the central office and your home, up crops another analog-to-digital conversion to sabotage your 56k connection. Some local lines also run through an amplifier called a load coil to boost the signal rates across longer distances. Load coils cause some signal distortion and will detrimentally affect your modem's 56k throughput potential.

Checklist

•     Make sure that you have the latest driver for your modem.
•     Look under modem settings to make sure the maximum connection speed is set to at least 57600.
•     Call US Robotics site at 1-847-330-2780 using HyperTerminal (go to Start -> Programs -> Accessories -> Communications -> HyperTerminal and make a new connection) to verify whether you phone lines are supporting 56K or not. When connected use "line" for first name and "test" for last name.
•      You may have to repeat this for few times to get an accurate result.
•     Contact your phone company to check your line for noise.
•     Using a modem string may help your situation.

Please note that our equipment is fully digital and supports V90 and K56 modems.