A Blackberry Enterprise Server (BES) developer works on creating, maintaining, and enhancing software solutions primarily for BlackBerry's business and enterprise customers. Their tasks include designing and implementing new software applications, troubleshooting and resolving issues in existing software, and ensuring optimum performance and stability. They work closely with other IT professionals for system integration and are expected to follow best practices for software development. They also need to possess a deep understanding of server-client architecture, mobile device management, and BlackBerry's proprietary technology. Their goal is to provide robust, secure, and efficient communication solutions for businesses.