a bit more info, so wrong assumptions aren't made.

Tried the laptop on a friend's phone line
Your friend is signed up to dial-up service and the service works fine for your friend's computer?

Are you getting an error message code?

Does the dial-up service show up under Network Connections in your Control Panel?

We MUST have more info, guessing is just a waste of time for all of us. Give detailed info on exactly what is happening and info on your pc and the OS so we know what we are dealing with.
Dose the laptop have a dial up modem installed?

Has it ever worked? Was the external DUN configured? I second RC's question, does the laptop have a dial up modem physically installed? If so, was it configured?

DA

I am running XP on a Sony Vaio

I was using it on Juno dial up for 3 years

Suddenly the no dial tone message

All I need to do to try the laptop on another phone line is to change the # I am dialing from

No dial tome error message #640

yes it shows juno on the network connections

I was hoping someone knew what is wrong, before I mail the laptop to my friend in NY

Thanks for your input

I'm assuming that you have tried unplugging the laptop and then plugging the wire into a phone and checked to see that it had dial-tone just fine, right?

I have a laptop which has to use an external modem.
The first external modem had the dialup sound.
Bought a new external modem----No dialup sound.
They now make them "Soundless"!

Have you tried a different Juno dial up access number? They do change them and some fail to function.
Agree most now are sound less.
Were you able to get a connection to dialup on some other phone line or Internet provider?

Were you able to get a connection to dialup on some other phone line or Internet provider?
She said in the OP that it works via Wi-Fi.

In an email she told me that she gotten an No dial tone error code 680 (not 640). She also said that she had tested the line by plugging the line into a phone and the phone had dial-tone.

Have you tried a different Juno dial up access number?
If there is no dial tone, you couldn't dial, right?

Goodness, it's been a LONG time since I had to troubleshoot a modem. Windows Hyperterminal and the Hayes AT commandset. Was it something like &ATDT to get a dial tone?

Error 680 seems to point to a hardware failure but it might be something else as well. I'd delete the modem in device manger, turn off the computer, unplug the modem, reboot the computer, once Windows is fully up plug in the modem.

Yes I know she said it works on wifi, what we need to know about is the on board dialup modem, which is why I asked if it has connected on any other dialup connection. She mentions a friends phone but gave no results???
If setting were changed might try a system restore.

I seem to remember my old laptop you had to unplug the network cable & disable wifi... before the dial up modem would work ... for that occasional fax.

I had a fax machine calling my phone one night.. all night,,, like every fifteen minutes.. ring ring.. beeeeeeeeppp.....finally i rigged the laptop to answer it to stop it. Was some company in a foreign country asking quote on huge order of ??screws or something simple. grrrrr

Ok...in an email she wrote, "I even tried it in the outside direct line box
We also have a desk top and that works fine on the dial up"

I found some possibilities at the link below.

I think I would probably just try a system restore first though.

Here is a link that might be useful: How to Troubleshoot

Yes system restore would be quick and easy and it's easy to reverse,
Start, all programs, accessories, system tools, system restore, select a date before the problem started, and restore.