This dissertation addresses some of the fundamental parameters for opening network architecture towards the new concept for creating multilayer and multiservice networks. It is based on principles of modularity and openness. The architecture must be open and based on open network platforms to fulfil present and future requirements. It is an essential element for ensuring uniformity of network usage and separation of information space of the call and service space. The unique element for connecting these two spaces is call process which is starter for data and events flow in an information space of the collaborating communication technology elements. The service is result of call process on network level. Evaluation is chosen as basic concept for new network development. It means that existing network elements must be taken in consideration when implementing some new ideas. That is the reason why is information analysis so important for service and co-operating technological elements. It gains the answers for QoS requirements. The issues of defining open software platform for usage in telecommunication is specially addressed. Platform must be at least robust, scalable and serviceable to comply with QoS requirements. In order to connect service and call space, the trigger mechanism was introduced. It transports information entities between calls information subspace and services information subspace. The basic intention is to use generic mechanisms in selecting data and protocol model to be independentable as possible from final technological implementation. Service triggered by call was defined to separate execution of call process and service logic on two different platforms. Associate data and protocols needed to support service were also defined. Call process is handled on standard switch platform and service logic on open network platform, connected with switch by trigger mechanism. Architectural concept was proposed to make practical execution of proposed service model. Mathematical model of analysed system and simulation model for vital components was defined to determine information characteristics of proposed service model. Finally, practical verification on modified system was made. All results give positive feedback what proofs the possibility of practical implementation of trigger concept with open network platform. The results show minimal impacts on standard call handling process in the switch with minimal quality disturbance. At the end the whole concept has additional proof for evolutionary development concept.