Confused about Brokering/factoring

Hi, so I have weird question. I am in the process of helping to start up a freight brokerage through my buddies plastic commodities company. The company does approx. 500 loads of plastic regrind a month(mostly out of Houston and in the Midwest part of the country). I have access to all of these loads, and a healthy amount of money in the bank. I'm posting a lot of these loads through the various forums, and getting a pretty decent response. Then we get to the payment. I tell everyone we can pay up front through an ACH transfer (50% upon pick up- 50% when we get a signed BOL) or through comcheck. We can't get factoring for at least 6 months to a year (even if we send the factoring company money up front). But it seems like when I tell people I don't have factoring, 7 out of 10 people hang up on me. I get that there are a ton of shady brokerages out there and we are new, but I don't really know how to gain trust with carriers any other way then we are literally paying up front. Any advice or thoughts would be greatly appreciated.