Frequently Asked Questions about 56K

What is 56K?

56K is a high-speed data technology that lets you receive data from a compatible Internet Service Provider (ISP), online service, or corporate LAN over standard phone lines at uncompressed speeds up to 56 Kbps, roughly twice as fast as a conventional analog modem. Data going in the other direction is transmitted at normal modem speeds up to 33.6 Kbps.

When 56K is not supported or a 56K connection cannot be established for any reason, the Zoltrix 56K works like a regular 33.6 Kbps faxmodem.

When will Zoltrix release a firmware upgrade to support the new V.90 56K standard?

Yes Zoltrix was the second company to release the Flash ROM upgrade to the new V.90 standard on 4-14-1998. All Zoltrix 56K models now support V.90 or are Dual mode supporting both V.90 and K56Flex.

How can I tell which protocol (K56Flex or V.90) is used by my Dual mode modem when I connect to my ISP which also supports both protocols?

In most cases V.90 will be selected by the two modems since this is the first choice of all dual mode V.90/K56Flex modems. But, you cannot be sure if the modem is connecting at V.90 or K56Flex in all cases. If the modem connects at a rate that ends with 333 or 667, for example 45,333 or 46,667bps, then you are connecting at a V.90 rate. But some V.90 rates are the same as K56Flex rates.
K56Flex starts at 32,000bps and goes up in steps of 2,000bps.
V.90 starts at 28,000bps and goes in steps of 1,333 1/3.

V.90 connect rates:

29333, 30667, 32000, 33333, 34667, 36000, 37333, 38667, 40000, 41333, 42667, 44000, 45333, 46667, 48000, 49333, 50667, 52000, 53333, 54667, 56000

Note: Some chip sets display the 667 rates as 666. For example The actual connect rate of 50666 2/3 can be displayed as 50667 or 50666.

K56Flex connect rates:

32000, 34000, 36000, 38000, 40000, 42000, 44000, 46000, 48000, 50000, 52000, 54000, 56000

As you can see, both V.90 and K65Flex share 7 different connect rates as follows:

32,000
36,000
40,000
44,000
48,000
52,000
56,000

If you are connecting at one of these rates, the only way to know if you are connecting with V.90 or K56Flex is to use the command to force V.90 or K56Flex for your model. Refer to the AT Command manual found on the modem drivers page for information on controlling the modems connect rate and protocol used.

Why can't I use the Zoltrix 56K to send data at 56 Kbps?

Sending 56 Kbps requires special equipment connected to digital phone lines (like ISDN or T-1). The Zoltrix Modem is optimized for browsing the Internet and World Wide Web or downloading information from a "central site" like an ISP, online service, or corporate network.

How do I know if my ISP or Online Service is supporting K56flex?

Many ISP and online service providers use Rockwell technology exclusively and most others use mixed technology that includes Rockwell. Therefore the likelihood is that K56flex will be supported at some point by your service provider. Of course, some providers will implement 56K technology faster than others. The best way to determine whether you can use 56K is to ask your service provider. Remember to make sure that they are supporting the K56flex standard.

How can I tell whether my local phone line lets me benefit from 56K technology?

56K provides speeds significantly higher than 33,600 bps for over 80% of local phone lines. There are two ways to tell whether 56K is likely to work for you:

If you have a V.34 modem and regularly connect at speeds of 21,600 bps or higher, 56K will likely work for you.
If you are 3 1/2 miles or less from the telephone switching office, as are most city and suburban phone lines, you will likely benefit from a 56K modem. Some rural phones may be further away, making 56K communication unreliable or impossible.

To determine your approximate distance from your telephone switching office (also called "central office"), you should call your local telephone company service representative. (The number is in your phone book.) Give them your phone number, and ask them for the address of the central switching office that handles your calls. Then look up the address on a local map and estimate the distance between your location and the "central office". If it's less than 3 1/2 miles (18,000 feet), your phone line probably supports 56K technology. If it's more than 3 1/2 miles (18,000 feet), it probably doesn't.

Can two K56flex™ modems connect at rates higher than V.34 when used in a home-to-home connection?

No. The K56flex™ technology is uniquely designed for home-to-ISP connections with the condition that one end (typically ISP site) has digital access to the telephone network and the other end (typically end-user) connects to an analog phone line. However, K56flex™ modems will automatically connect to each other in V.34 mode when used in home-to-home connections.

Why can't I connect at K56Flex rates?

The most common barrier to 56k performance, is the presence of a SLC96 (slick) concentrator in your neighborhood. Telephone companies install a SLC96 to split up lines in existing phone hubs to add more lines in high-growth areas. This split nullifies the 56k capability, dropping all lines down to a maximum v.34 specification. A second barrier occurs when a phone line is stretched beyond 18,000 feet from a telephone company office, which is beyond the effective range of the 56k
technology. This occurs primarily in rural areas. Corporate offices that are using PBX systems will lose 56k capabilities due to line attenuation.

Check with the phone company to see if the above applies in your situation.

Another cause could also be the connectors and wiring in your house.

Following is from a user or a K56Flex modem.

Like a lot of us I also was having trouble with the 56k!
I have both the 56k access lines and a 56k modem!
But usually I would only connect at 21,600 (sometime 44,000 bps if I was Lucky)
My average speed sucked only being 17,000 bps!
My high was 27,000 bps and my low was 500 bps!
I also kept getting error messages!
If you are like me, you thought the Telephone Company had bad wires!
But then I thought about my house's plugs (I have a Old house with Old jacks)!
So I cleaned the connector pins on all the cords I was using, I clean The Jack's connector pins I was plugged into and the Wire inside the jack!
I clean them with a fluid that cleans connector pins! (AKA video game cleaner!)
I clean everything until it turn from a dark green to a Bright Brass-e Color
And WOW! I connect at 50,000 bps every Time and get no errors and My Times are great with 37,000 bps being my average
28,000bps being my lowest and highest being 44,000bps!
What Great improvement huh!

* Capable of receiving at up to 56Kbps, and sending at up to 31.2Kbps. Due to FCC regulations on power output, receiving
speeds limited to 53Kbps. Actual speeds vary. Requires compatible phone line and server equipment. Complies with both the
V.90 56K standard and K56FlexTM technology protocols. Test your phone line here for compatibility before you buy.