Find the COM port for TAPI devices

Question

I use RASAPI32.RasEnumDevices to determine which RAS devices (ISDN or Modems) by name and type are connected to my computer. I use System.IO.Ports.SerialPorts to list all of my COM ports which also shows if a modem device is connected. I use these devices in connecting to the internet. The phonebook entry for the device is created on-the-fly.

What I need now is to put it together. How or where can I find out in WIN XP which RAS Device name is on which port. I need the port for issuing AT commands. I use an analog modem, an ISDN FRitz Card and a UTMS modem card.

WMI.POTSmodem does not list any of these devices.

Coding is in C#