Dial up networking timing out

Hello All,
I'm writing an application which does FTP file transfers via the internet. I'm using the MFC classes CInternetSession, CFtpConnection and CInternetFile to accomplish this. The transfers work fine, my problem is with Dial Up Networking. If DUN is set to automatically hang up after x minutes of inactivity, it will hang up after x minutes even if there is activity, and the connection has to be re-established. DUN does not seem to be detecting the activity. This happens on NT, I not sure if it also happens on 95 or 98. Any one have an answer or a work around? Thanks. -gb