iSupplier portal - direct deposit information incomplete

We are experiencing an issue with suppliers in iSupplier portal that are setting up their banking information and not including their routing number.  When we receive notifications of the banking information we reject it because of the missing data.  Unfortunately the notification to supplier does not state why it was rejected.  Curious if we make this a required field to fill out, how it will impact other suppliers that do not have direct deposit and how it ties to the record.  Other option was adding a tip above the line.  How are other Oracle users handling this with their suppliers?