The document discusses potential solutions for integrating two different versions of Siebel. It evaluates Universal Application Network (UAN), Websphere Business Integration (WBI), Siebel Integration Layer, Siebel Master Data Applications, and a third-party custom application. Each solution is described and evaluated based on criteria like complexity, coupling, reliability, and simplicity. The document concludes that the Siebel Integration Layer provides the best solution due to its simplicity, flexibility, time to market, and reliability compared to the other options. Diagrams of sample architectures are also included in the appendix.