Pulling information

I have 3 tables: 1.Assets 2. Contacts & 3. Maintenance calls.
If I have a form to start a call for a repair and I ask for a phone number, how can I add automatically to the form (or later, to the table itself) the info about his contact details and the asset, based on that (the assets and contacts are linked together)
Thanks a lot

Hey there! I think that you probably want to just create a link to the call from the contact, and a link to the assets from the calls.