Let me see if I can try to explain it, okay?
Your Company field in your form is a lookup. It is using an ID (number value) for the value of the field (which is what is actually stored) and it displays the company name based on that ID.
So let's say you have some rows in your contacts list (which is what provides values for your Company lookup) and they look like this:
ID Name
1 Sam's Sub Shop
2 Mary's Hair Hut
Your form would be storing either 1 or 2, based on what was selected. But since it is a lookup and is looking things up based on the ID that is stored, it displays the name - Sam's Sub Shop or Mary's Hair Hut.
Thus, in your filter, you want to select items (like Phone) based on the ID in the Contacts list being equal to the ID that is stored in the Company field.
Did that help, or just make it more confusing?