The following is from Don Hinds - Senior Zoom Tech

56K Modems

NOTE: You cannot buy two off-the-shelf 56k modems and connect 56k between them. The host site must have a special modem \ connection to special digital equipment.

*** Even between Rockwell 56K modems you will not see any full 56k connections because at this time the maximum the phone line can support is about 53K. You are likely to see speeds in the mid 40s or even 30s because of fallback due to less than optimum line conditions. Even if your phone line supports 56K, the other line or the trunk line may not. And every connect speed may not be the same. You may connect anywhere from 38k-44k on the same phone line in the same hour. The phone company does not route every call the same way.***

You are more likely to see higher speed connects on long distance calls, because the lines are newer and cleaner than many local lines. At this time many telephone lines will not even support a 'full' v34 33.6k Connect. Most often you will see V34 Connects.

*If you are having trouble connecting at 56K speeds, try putting S202=32 in your init string. AT&F&C1&D2S202=32

*If the response seems slow after you connect, try going to 16650 UART Settings of the Modem, and set Transmit Buffers to the ¼ mark (send speed at 56k is slower so it doesn’t matter). Set the Receive Buffers to Max or to the ¾ mark.

If you flash upgraded your 56k modem, delete it from your modem list in the Control panel and re-boot the computer, then re-install the modem. Put the new mdmzoom.inf file on a disk in A: and when it gets the list to pick a modem click ‘have disk’ and pick from the new list.

NOTE: While it is theoretically possible to use a setting of 230K, at the present time most computers, drivers and so forth are not equipped to do so. You would not see any appreciable (if any) increase in speed in any case. 230K assumes maximum speed of 56k connect speed (impossible) and maximum compression of 4X (very unlikely).

NOTE: 56k modems automatically fallback to slower speeds if the line is not good for the current speed. Newer versions of 56k code probe the line more aggressively and may have a lower original connect speed. But they are less likely to have fallback than earlier code. When lines improve you will get faster speed with no changes on your part.

NOTE: The internet at times is VERY slow. When traffic increases, transfers may slow drastically, sometimes to a standstill. The same often holds true for large services like Compuserve, though they are a lot better than they used to be.

BTW, there is a website for 56K info and answers. http://www.56k.com (note from starck, I have never found this site even though it is mentioned in this email from Zoom)

Line Quality

To test the quality of your lines on v32bis modems, Type +++ and wait until you get OK. (do NOT press [Enter]). This puts you in command mode. Then you can enter AT%L?%Q? and it will give you numbers for signal level & line quality. You should get 15-30 for %L? preferably 18-25, and for Q? lower is better. 11 or below is what you should get. You can try forcing higher speeds to see if quality drops at the higher speed, or force lower to see if quality goes up. (To go back online enter ATO). NOTE: some modem work with the AT%L? only. Sometimes your speeds may go down. If the phone company installs a Mulitplexer on your lines you are likely to lose speed. They install Multiplexers so they can put more phone lines on fewer phone wires, and your speed suffers.

Line Noise

If the characters that appear on the screen after you connect are ALL illegible, then the following does NOT apply. If Some parts of words are readable, or you have trouble downloading (CRC errors), then the following probably is the problem, especially if it is worse at higher speeds. It may stop altogether at lower speeds. Line noise may also be the cause of FAX or 56K not connecting (or random spots on faxes).

Commonly called line noise, problems with downloading or the spurious characters or garbage that appear on the screen are usually from the central office of the phone company. It can make a big difference whether you call Out or someone calls In. Also there is a difference between calling different areas (area codes or exchanges) as different equipment will be involved. Calling the phone company will rarely do any good, because the problem is not on your line. It is also much more likely to happen on local connections than long distance. Older cities are more likely to have problems.

For more information on line noise and possible cures check the following web pages.

(the following two references have not been found to be live but they are in the email from Zoom) www.jdsm.com/noise.txt
www.eng.usf.edu/~wirsz/text/noise.txt

NOTE: ZOOM cannot and does not endorse or recommend any circuits on those pages. You use them at your own risk. I provided those Web addresses for informational purposes only.

(The only commercial device I ever tested that claimed to stop noise, cost more than $45 and did nothing at all).

Don Hinds - Zoom Tech

Ps. My 56K modem would not connect at all from my home (2.5 blocks from Telco Bldg) until I made and used one of those ‘filters’.

Don

Itu international standard V90 for 56k modems has been generally approved by all parties. It is expected it will be ratified by a vote later this year. You will begin to see ITU V90 56k modems from all parties very soon. Zoom is now shipping dual protocol (K56Flex/V90) modems.

Do you need to upgrade to ITU V90? If your present ISP uses K56Flex modems then you should be OK. When they upgrade they will normally upgrade their modems so they will support K56Flex/ITU V90. All their old users will still be able to log on at 56k speeds. It is up the individual user When you upgrade to ITU V90. Only if you change from one ISP to another will you need to upgrade if the new one is X2/v90. Many ISPs will not be ITU V90 compatible for a while. There is still the small possibility the standard may change since it has not been ratified yet. In any case, unless you change ISPs to one that used to be X2, you are unlikely to even need the upgrade for the forseeable future.

We will post ITU V90 upgrades on the website as they become available. It takes a little longer to do upgrades than to do a new modem, since the flash has to be tested to make sure they do not corrupt the various models when they are flashed.

If you have an 1M eprom the upgrade software will call your ISP and check to see if it has upgraded to V.90. If it has then you will be allowed to upgrade your modem. If you upgraded to V.90 and your ISP had not, you would be restricted to V.34 until your ISP upgraded to V.90. That is why the software checks before it allows the upgrade.

We are shooting for early April for upgrades..

Don Hinds - Senior Zoom Tech

Use AT&FS202=32S95=1&C1&D2 as the initialization string.

Here are some other suggestions This should help you troubleshoot K56 FLEX connect problems....

1 You need to check your modems ROM revision, you may use the ati3 command in any Communication software to do so. (eg.ComitW/Procomm/HyperTerminal)

You also need to check what version your ISP is using. ROM updates for the Zoom Internal and External modem is currently posted at...

http://www.zoomtel.com/k56/k56-files.html

2 There's a alternative list of K56Flex providers posted on our Website at http://www.zoomtel.com have you tried connected to any of these numbers.?

3 Have you been able to connect to any K56Flex service at 33.6+ speeds.?

4 You may also use the modem +MS register (see p.49 in Owners Manual) to force Protocol and Min/Max speed like so....

AT&FS95=44S202=32+MS=56,1,36000,56000&W

AT&FS202=32%C1+MS=56,1,36000,56000&W

AT&FS95=44S202=32+MS=56,1,38000,56000&W

AT&FS202=32%C1+MS=56,1,36000,56000&W

AT&F&C1&D2%C0S202=32+MS=56,1,38000,56000&W

AT&F&C1&D2\A2%C1S202=32+MS=56,1,36000,56000&W

AT&F&C1&D2\A2%C1S95=1S202=32+MS=56,1,38000,56000&W

AT&F&C1&D2\N5\A2%C1S202=32+MS=56,1,36000,56000&W

AT&FS95=44S202=32+MS=56,1,36000,56000&W

AT&FS202=32%C1+MS=56,1,36000,56000&W

AT&F&C1&D2%C0S202=32+MS=56,1,36000,56000&W

AT&F&C1&D3&K3S202=32+MS=56,1,40000,56000S95=1 REMEMBER!! Init Strings for Internet are inserted under Dial-Up-Nets "Extra Settings" dialog box.

5 It's usually easier to use HyperTerminal or a Terminal Window under Dial- Up-Networking to dial your ISP's access number like so...

AT&FS95=44S202=32+MS=56,1,36000,56000&WDT

the advantage is that with S95=44 in your string the modem will report all speeds and Protocols including Carrier speed.

Dial-Up-Net may report Connect (DTE) speed which is a software compression setting, much more important is Carrier (DCE) speed, you may need to
try the following...

1 Include S95=44 and/or W1 in your string under "Extra Settings'.

2 Use a "Terminal Windows" to dial under Dial-Up-Networking.

3 Under DUN check "Record to Logfile" and see contents of modemlog.txt

Regards

Lori
Zoom Technical Support

PS: Please try the above BEFORE attempting a ROM update, I also need the modem ati3 command response and your ISP's Access Number. This could be a line-noise problem.