Would this not be covered when a contact will just email you? Then you can just grab their details and fill in the sections needed.
Having a signup page, the risk is to have the form open and anyone can just register with real or fake accounts, which gives the tech/admin additional task to verify details and approve or not the contact.
Personally, i don't see the need of the contact himself to register to the portal, the way this is implemented now, works just fine.
More or less, if contact will email support@ that goes to ticketing, you already have a start of adding the contact to the system. so if you are at the expo, you can hand out business cards and future possible leads, can just email you instead.
Alternatively, on your own website, you can create a Call back/Quote form for possible leads and that cand be set to just email the submissions to your itflow as well.
