USB dialup modem problems

I just installed a Nexxtel USB modem (when plugged in it shows up on my device manager as an Agere Systems Usb 2.0m soft modem)on my MSI U100 439 WinXP and it seems to connect to my ISP nicely, but I can't access any sites on the internet. It shows up at 50 kbps, but every site comes in as unavailable. I even tried shutting down my antivirus and Zonealarm temporarily, and that didn't help. My wireless is disabled- I use a USB dongle (the built-in has terrible sensitivy) and so is the network connection, which I don't use. I mentioned Windows XP, and I used the cd that came with the modem for installation with no problems. I also think I mentioned it does connect to my ISP with username and password verified. It's an old dialup connection through the phone line which I want to use when I can't access Wifi. The problem is, once I'm online any site I search for comes up after a minute or two as unavailable.

Any ideas?

 

While on dialup, start > run > cmd, hit enter.
Type in "ping google.com" without quotes.
Type in "ping 4.2.2.2" without quotes.
Do either of those work? Do both of those work?

 

In both cases request timed out. packets sent 4, received 0. 100% loss.
To check modem, I disabled PCI modem in a desktop, also Windows XP, abnd installed the USB modem. It installed and functioned perfectly-no problems.
Why not in the MSI Wind?

 

Start > run > dialer
see if you can get it to dial your cell phone.
There is also an option in device manager (I will have to go on memory here, I have no computers with a modem at my disposal)
Right click the modem in device manager > properties > diagnostics > query modem
If you get a command success or something like that in the results, XP is detecting your modem properly.

 

There might be a conflict with your lan. If that's the case there are workarounds, but for now, try disabling any lan connections and retry the dialup.