When deciding to sign a contract with a customer you need both interpersonal skills and business knowledge. From experience working with suppliers, you need to be knowledgeable of the product, risks, financial obligations required in persuading your team and vendor to commit to a contract. In addition, you need interpersonal skills especially as the leader/spokesperson of the company. In order to create compromise contract which is favorable for you and your customer you need to persuade the customer using your interpersonal skills. Some leaders do not have interpersonal skills which can result in a fall out with a customer because, even though you have the business knowledge, if the customer is not able to communicate with you with confidence then they will hesitate to sign any deals.