HELP: Internet / Call Waiting - no missed call while using the internet

[yaco]

My girlfriend gets pissed everytime she calls me and goes straight to voicemail because I'm using the internet... which I use a lot because of my unlimited data plan (Sprint PCS/SERO).

This got me thinking there must be a way to still receive the notification that someone is calling while I'm using the net on my phone since all I'm really doing is being on a phone call but calling #777 instead of a friends number, right?

If I can have call waiting for a normal call, why can't I have it when I'm on the net? Is this possible? do I need a new plan, phone or do I need a new girlfriend?

Sorry if this is posted somewhere else, I just couldn't find it. Thanks,

-YACO