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Slow Connection Speeds
The speed reported by the modem is the initial connection speed
The speed reported by your modem when connected to the Internet may be lower than you'd like it to be. It is important to note that the connection speed that is reported by your modem is the initial connection speed. After connecting, adjustments and changes to the speed will occur. The modem may attempt to speed up (fall forward), but will slow down (fall back) when excessive transmission errors occur that prevent the modem from sustaining the initial speed. Some modems are agressive, and attempt to connect at a high speed then downshift, while other modems connect at a conservative speed and attempt to upshift during the connection. When a modem tries to achieve/maintain speeds that are beyond the line's actual capability, you end up with a lot of errors and speedshifts which result in poor throughput and performance. See Why Slower may be Faster from modemsite.com for more information.
What is the average speed for a v.90 modem?
If you have a v.90 modem, the average connection speed is about 40-49kbps. If you have a 56K modem and your connection speed is less than 38kbps, the low speed is likely due to a bad line condition, multiple A/D (analog to digital) conversion or Telco issue.
Are you connecting at a v.90 speed?
Click here for a list of v.34 and v.90 connection speeds.
Multiple A/D Conversions prevent v.90 connections
The phone line going from the modem is analog until it terminates into the phone company's central office (CO) or digital loop carrier (DLC). If there is more than one analog to digital (A/D) conversion present on the line (see below), you will not get v.90 connection speeds; instead, you will get v.34 connection speeds. See A/D conversion check for more information.
More than one A/D conversion on the line can be attributable to:
- Old equipment Some older switches may cause an additional analog to digital conversion.
- Pads Pads may be used on the line to make voice communication the same volume both ends during a telephone conversation. An analog pad introduces additional A/D conversion. There are also digital pads which do not affect the connection speed.
- SLCs If your home (or office) is attached to the Telco Central Office (CO) using a non-integraded/universal DLC, also known as an "SLC", you will have more than one analog to digital conversion. If, on the other hand, the SLC is directly integrated into the digital telco switch, you should get a v.90 connection unless the options or timing are not correctly configured by the Telco which would result in poor throughput and unreliable connections.
Other factors that affect your connection speed
In addition to multiple A/D conversions, other factors that affect your connection speed include:
- Distance from the Telco Central Office (CO) If you are more than 18000 ft from the Central Office, you will get a 33600 connection speed at best. The closer you are to the CO, the better chance you have of having a higher connection speed.
- Multiplexing equipment This equipment, also known as Pair Gain Devices, are used to provide a second phone line or increase the number of customers that can be served can limit the line connection speed.
- Digital lines Note that while a digital line will
provide a cleaner data environment, it may limit the
maximum speed a modem may attain. There are also different types of digital
subscriber line systems. Some combine many lines into one digital carrier,
others combine only two. The key to having V.90 capability with one of these
is the way the carrier is interfaced into the digital telco switch or even
being connected to a digital switch. If the digital line does not use an analog to digital interface, a device you can use to remedy this problem is the Mobile Konnector.
- Sychronization Synchronization issues in the switching center that causes your modem to repeatedly "retrain" - probe the line for configuration parameters.
- Load coils or signal amplifier These devices are installed on analog portion of line by Telcos to boost the voice communications but which may also distort the signal and reduce a modem connection speed.
- Call routing Phone companies may change the route the call takes at certain times of day to distribute heavy traffic on the lines. This might also occur during road construction. This change in routing may introduce an additional A/D conversion on the line, thereby lowering your connection speed.
- Signal strength Phone companies may also lower the signal strength on the line during times of high usage.
- Noise on the lines. Caller ID, portable phones, and answering machines can all add noise to your line, limiting the effect. Even high-tension power lines in the vicinity of your home, or near the route your line takes can cause enough electromagnetic interference to cancel the advantage. Connect a telephone to the wall jack used by the modem, pick up the line, dial the number 1 to stop the dial tone, and listen. Do you hear loud hissing, static or voices? Try the test again after disconnecting other telephones and devices using the line. Still hear the 'noise'? Before filing a complaint with the phone company, please bear in mind that the phone company is only obligated to provide 9600 bits per second on that line, which is adequate for the business they're in - voice communication. In addition, noisy lines can also be due to INSIDE wiring.
One way to test INSIDE wiring is to by-pass the home wiring and connect your modem directly to the demarc - a gray box where the phone service enters the house. If the noise disappears, then the problem is due to inside wiring. See Disconnects for additional information and possible fixes for issues such as line noise.
- Hardware incompatibilities Some modems are not as compatible with our modem pool than others. For example, we do not support the v.92 protocol and there are some v.92 modems that do not work extremely well with our service unless the v.92 is disabled (use v.90 instead). In addition, older 56K modems using the X2 protocol may experience problems. The workaround for these modems is to disable the X2 protocol with a modem initialization string. See Modem Initialization Strings for more information. Note: It is strongly recommended that you update your modem driver (when updates are available) as these updates may sometimes improve the connection.
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