What's an X2 modem?

[andrej hocevar <ah@siol.net>]

Hello,
recently, someone's gave me an older internal USR V.90 modem,
supposed to work at 56k. However, all I got were speeds at about
33k. That was when I noticed the modem uses some X2 technology. 

Can I make such a modem useful? I've read some sites saying it
depends on the ISP -- so does it mean mine doesn't support it or are
X2 modems simply out of fashion? Is there any software I lack to
make full use of the modem?

thanks,
	andrej

-- 
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