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Service Hints & Tips

Document ID: LWIK-458KXF

TP 600,770 - Problems connecting at V.90 speeds or low V.90 connection speeds

Applicable to: World-Wide

SYMPTOM:
Getting V.34 connections, 31.2kbps or less, using TP V.90 modem.
Getting V.90 connections at lower V.90 speeds, around 32kbps.

CONFIGURATION:
TP 600 or TP 770 with V.90 modem upgrade installed.

Note: Not all ThinkPad 600's or 770's come with an ACP modem.

WORKAROUND:
From many calling locations, a V.34 connection is a successful connection for a V.90 modem.

ADDITIONAL INFORMATION:
Background
The majority of phone lines in North America will support V.90 connect speeds. However, there are some phone line configurations that will not allow V.90 connections and will cause the modem to drop back to V.34 rates. Industry estimates of lines not allowing V.90 connect rates, range from 5% to 20%. For connections through PBXÆs, typical for offices and hotels, these estimates are higher, 10%-30%.

The TP600 and TP770 V.90 modem supports connect speeds from 53kbps* down to 32kbps. Most telephone lines that support V.90 connections will support connections between 40kbps and 48kbps.

There are some phone line configurations that will cause difficulty for high speed V.90 connections. This is primarily due to line impairments. Line impairments are telephone network conditions that create difficulty for high speed modem connections. Line conditions and configurations can change, therefore lines that are not capable of high speed V.90 connections today, may be capable in the future.

Requirements for connection at V.90 speeds

1. The ISP/server modem must be connected to the telephone company central office via digital lines. Knowing that the ISP supports V.90 is usually enough to verify this. It is this digital connection used by the ISP/server modem that allows V.90 technology to work.
2. Both the client (end-user) modem and the server (ISP) modem must support V.90.
3. The client modem is connected to the telephone network via analog lines. There can only be one change from analog to digital lines, between the client and server, for V.90 connection speeds to be possible. If there are more than one change from analog to digital lines, then V.90 speeds are not possible and the modem should drop back to V.34 connection speeds, 31.2kbps or less.

Possible Causes

1. Any of the Requirements for connection at V.90 speeds above not being met.
2. Any of the causes listed in the following document: TP General - Problems connecting at 56K speeds.

Things to try that could possibly help

1. Latest modem drivers on client modem.
2. Different location for calling modem.
3. Different phone number for ISP/server.

Articles about V.90
http://www.zdnet.com:80/computershopper/edit/cshopper/content/9902/383154b.html
http://56k.com/cons/
http://www.v90.com
http://www.computers.com/reviews/comparative/substory/0,29,0-14-257672-667659-1,00.html?sr.co.crr.inav.crsu667659

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	Document Category	Communications
	Date Created	18-02-99
	Last Updated	26-02-99
	Revision Date
	Brand	IBM ThinkPad
	Product Family	ThinkPad 600, ThinkPad 600E, ThinkPad 770, ThinkPad 770E/ED, ThinkPad 770X, ThinkPad 770Z
	Machine Type	2645, 2646, 9549, 9544
	Model	Various
	TypeModel
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