Your dial-up connections are located in the Remote Access Phonebook (Rasphone.pbk) at
\Documents and Settings\All Users\Application Data\Microsoft\Network\Connections\Pbk.
NOTE: Since the Application Data folder is hidden, use Windows Explorer to select the All Users folder. Use Tools / Folder Options / View to check Show hidden files and folders and press OK.
Copy the Rasphone.pbk file to another folder for safe keeping.
To restore the phone book, copy it back and restart your computer.
To move it to another computer, copy it to that computers
\Documents and Settings\All Users\Application Data\Microsoft\Network\Connections\Pbk folder and restart that computer.