Digitize account payables

We currently have to route a paper invoice around to multiple approvers. it would be time saving to upload invoices in to the vendor master, and assign task(s) to the approver (such as "sign invoice" or, for partial orders, ask if the order were fully received. Approvers will be able to digitally respond and sign invoices. Another option would be to give the AP invoice process the same features as a work order, but "digitally". Other companies are offering integration software packages, but why not be within the same suite.