We want to track offline actions from FB ads, calls, and we're trying to figure out if it's possible to fire a postback url into Facebook to trigger a conversion. I realize you need a cookie in here somewhere to fire the typical FB pixel, but I'm wondering if there is any kind of workaround?
Nope. FB conversion tracking is JS/Cookie based and needs to be done by the user.
The workaround I would recommend is using a PMD that can use postbacks for conversion tracking.
PM me if you want some recommendations.
You'd be looking at minimum $500/mo overhead and contract periods though (but you'd up your FB game considerably).