ave been switching over to the IP backbone. This means huge savings in investments for them. The aim of IP trunking and SIGTRAN planning is to convert an operator's network into an optimal IP based network solution, taking into account the current signalling network and future requirements. IP trunk planning consists of three main activities: assessment of the current signalling network; dimensioning of the IP based network; detailed planning of the IP based network. 4.12.1 Current Network Assessment The objective of assessment is to analyse current CCS 7 network architecture, topology, signalling plan, routing and traffic requirements in the short, medium and long term. The following factors need to be considered in the current network: Core Network Planning and Optimisation Geographical constraints Network architecture and topology Network capacity and technology Technical constraints Future demand requirements of services and capacity also need to be considered. The following inputs are required for Network Assessment: Network architecture Locations and naming conventions of network elements Network topology (both user plane and signalling plane) User plane traffic routing criteria (inter-MSC, interconnect to other networks, PLMN, PSTN) Control plane traffic routing criteria Signalling plan (CCS 7) SPC allocation Signalling link sets plan Country-specific regulations Traffic requirement Timeframe definition for the study Services (basic voice, value added services, Internet, etc.) penetration and forecast Subscribers Traffic/subscriber service Grade of service Once the above inputs are collected, the following tasks are performed: Network architecture study Signalling plan study Traffic requirement study 4.12.2 Dimensioning of the IP Backbone The objectives of dimensioning are to define the technical solution in the IP perspective, to apply dimen- sioning rules, to evaluate bandwidth requirements and to produce an 'IP signalling master plan'. The following are required for dimensioning the IP backbone: The tot