This thesis presents different experiences related to architectures and mechanisms for deployment of telephony services, understood as especial features complementing the basic voice service. The context for these experiences is the transition of telecommunication (telephony) networks from circuit switched based systems towards packet based ones. Service deployment in a specific hybrid PSTN/IN/VoIP architecture is presented as well as a description of the enabling technologies. Discussion on service implementation examples is provided. The convenience of network neutral service invocation is introduced and how this has been achieved, by means of Web Services-based mechanisms. A single-request / single response protocol for invocation of a specific set of services is presented and a decoupling mechanism between signalling network protocols and service logic invocation demonstrated. Services, have been designed, implemented and tested as part of this demonstration. Performance characterization of different service implementations is also provided. Finally, a data model for an overlay network to existing telecommunication (telephony) infrastructures, allowing operational convergence is described.