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Frequently Asked Questions about the V.90 56Kbps modem standard

The 56K modem war is over, with an important ITU agreement reached February 6th, 1998 in Geneva, Switzerland. Who won? Consumers and ISP's!

A compromise has been officially reached between the two modem camps. Central site equipment makers like Ascend, Cisco, Livingston and 3COM will release new code to allow ISP ports to be ITU V.90 compatible. As soon as ISP's deploy V.90 code at their POPs, users that get flash upgrades to bring their X2 or K56flex modems to run V.90 won't care what kind of central site equipment is at their ISP, both will work. And ISP's everywhere will breath a sigh of relief as they finally can forget about trying to decide to deploy X2 or K56flex central site equipment.

What is V.90?

V.90 is the new international standard for "56K" analog modems. Previously there were two competing standards-- K56flex (from Rockwell/Lucent) and X2 (from 3COM/USR).

How fast are V.90 modems?

With a reasonably good phone line and if you live within 3 1/2 miles from your central office (local phone company building), you should get connect speeds between 40K and 53K. Some lines have impairments on them, like digital pads or robbed bit signaling (RBS), which decreases the highest achievable speeds. However if you are getting pretty good V34 connections, you should be able to significantly benefit from a V90 modem.

If these modems can't really connect at 56K, why are they called 56K?

It was an unfortunate misnomer. The FCC limits legal speed on the Telephone network to 53Kbps. Actual speeds vary according to your phone line conditions. (...your actual mileage may vary)

Will I be able to connect to my ISP at V.90 speeds?

If you were able to connect to an ISP using K56Flex you should also be able once you and your ISP upgrades to V.90.

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:

28000, 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:

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.

I have a 56K modem but it only connects at 33.6 or lower speeds

Make sure you are calling a phone number that has a compatible 56K modem at your Internet Service Provider or AOL. Some phone numbers only have V34 modems on them and you cannot get 56K speeds calling these. Also, make sure you are calling a compatible line. If your ISP has K56flex running, you will not be able to get an V.90 modem to connect at K56 speeds. If you are still having problems connecting at V.90 or K56Flex rates, you can refer to the AT command manual for your model, (found on the modem drivers page for your model), to try forcing a specific connect rate or mode with dual mode modems supporting both V.90 and K56Flex.

I have a Zoltrix K56Flex modem. Can I upgrade it to V.90?

Yes, Zoltrix has released V.90 code for all 56K models, but don't upgrade until your ISP has. The FMVSP56i(2) and FMVSP56e Rockwell based modems, while flash upgradable to the new standard, can only hold one protocol at a time. A method will be provided to switch to run either V.90 or K56flex code, but there is no point in loading V.90 code yet. (Unless you want to turn you 56K modem into a 33.6!) If your modem can only run V.90, it cannot connect in high speed PCM mode to a K56flex ISP, until the ISP deploys V.90. We recommend waiting to do the upgrade. If your modem is working fine now K56flex mode, leave well enough alone. But if you want to upgrade to V.90 you should first ensure the following conditions are met:

Step #1: Find out if your ISP has upgraded to V.90.

Before K56flex modem owners can connect to their ISP using the ITU's new V.90 56Kbps standard, the ISP first must implement V.90 in its central-site modem equipment. K56flex is used in more than 65 percent of the world's ISP ports, and Rockwell is now working closely with leading ISP equipment manufacturers including Ascend, Cisco and Shiva to provide the necessary software to upgrade these ports to V.90. Those ISPs who have not yet offered any type of 56Kbps Internet access service are also expected to very quickly implement V.90 in the coming weeks and months. Most believe it will be several months until the majority of ISPs finish their upgrade to V.90. Before and after that upgrade is completed, all ISPs who previously offered K56flex service will continue to offer K56flex service. So K56flex will continue to be the most widely available and safest choice for consumers during the industry transition to V.90.

Step #2: Decide if you're really a candidate for an immediate V.90 upgrade

If you're already happy with your ISP's K56flex service and have no immediate plans to switch to another ISP, there is no immediate need to upgrade to V.90.

Because of the backward-compatibility of Rockwell 56Kbps central-site modem chip sets, all ISPs who currently offer K56flex-based Internet access service will continue to offer K56flex service even after they upgrade to V.90. Again, that's 65 percent of all ISP modem ports, worldwide, that will always offer K56flex service. The only protocol that will have broader proliferation is V.90 after it is fully deployed -- a process that is likely to take several months. So if you're already getting satisfactory K56flex performance and you like your ISP, no action is required of you regarding a V.90 upgrade. Plus, even if you do decide to switch  ISPs, it doesn't necessarily mean you'll need to upgrade to V.90 --  the widespread availability of K56flex service means it's highly likely that the new ISP also supports K56flex, and will continue to do so even after the ISP upgrades to V.90.

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:
  1. If you have a V.34 modem and regularly connect at speeds of 21,600 bps or higher, 56K will likely work for you.
  2. 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.

    3.  

     
     
     
     
     
     
     

    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 V.90 or K56flex™ modems connect at rates higher than V.34 when used in a home-to-home connection?

No. The V.90 and 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 or V.90 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.