2 internet connections

Hi,

I'm developping an application that will be always connected to internet through
a cellular modem. But this connection must not be used by my application.

Instead, my application will have to establish a connection to internet using a
conventionnal modem and the RasDial API function.

Once the computer will be connected to internet (RAS), I will have to send a file through the FTP protocol.

My question is how can I choose the (RAS) internet connection to send my file
instead of using the cellular one ? From the test I did once I'm connected to Internet by RAS, the network request are send through the cellular network instead of the RAS one.

Is there a way to force request to be sent through RAS network ?

Best regards,
Martin