VOLP - s an acronym for Voice Over Internet Protocol, or in more common terms phone service over the Internet. If you have a reasonable quality Internet connection you can get phone service delivered through your Internet connection instead of from your local phone company.
OSGi - OSGi technology is a set of specifications that define a dynamic component system for Java. These specifications enable a development model where an application is composed of several components which are packaged in bundles. Components communicate locally and across the network through services.
An application in this context represents the functionality desired by the organization. For example, an expense account reporting application or a payroll application. The goal is to make the application code as small as possible because that code is not reusable. It is the code that is unique for the application and usually highly coupled to a large set of components. That, however, works two ways. Since applications are not reusable extra dependencies are very cheap.