The most common problem users report is that the time and number of rings appears for a call, but no name or phone number.  If this happens all the time then please see the Troubleshooting section.  If it happens occasionally, it could be that the caller hung up the phone before the information was sent, or something happened to disrupt the caller information.  If the phone rang two or more times, and you have a hardware caller id device (such as a caller id box or a phone that displays caller id) so you know the caller information was apparently sent properly, it could indicate a problem with the modem, or too many devices on the phone line.  Of course, it could also indicate an unknown problem with Ascendis Caller ID.  You can narrow down the problem by examining the Windows Modem Log or the Line Monitor.