Today’s Telecom sectors’ implementations seem to be sub optimal and might even end up out of control because of the multiple implementation of technological and process functionalities, and dominant financial focus that complicates removing legacy networks. Even though, there is support for fulfilling customer needs, the inefficient use of resources can negatively affect the business activities and profits. The Telecom sectors’ current evolutionary stage requires a thorough evaluation of all its current implementations in order to restructure and consolidate them. In order to maintain the vital telecom contribution to our society and economy, cost optimisations and the ability to keep on innovating in an increasing complex setting, need to be safeguarded. We know that, apart from financial difficulties, there are important handicaps in this sector itself: it has an ill-defined set of functions that has been addressed by different standardisation bodies. This has led to the main research question, namely: How to identify a best of breed model which both reflects the current (2009) and the near future (2012) Telecom sector functionality in order to come up with an advise about optimising its internal functional structure taking into account the relevant requirements concerning interoperability with other sectors? The major objective of this study was to identify both the internal and external functions performed by the Telecom sector and thus reveal how they provide value to the other nodes in the sectors’ network. The Telecom sector (as defined in this document) is the research domain and subject of modelling in this thesis. Accordingly, the functional approach deliberately chosen for this project provides an implementation independent basis of knowledge that could be transferrable from the Telecom sector to other sectors or to different aggregation levels in the economy and society. The functions were extracted from well known and commonly used telecom related models. As a result, from the data mining and analysis applied to those telecom related models, this thesis provides a long list of 331 functions performed by the Telecom sector. In addition, these functions were mapped onto other non-telecom sector specific models that have a sectors’ network applicability in order to confirm the neutrality of the functional perspective. A minority of those functions proved to be Telecom sector specific. In this thesis, we present a proposition to classify functions, taking into account two dimensions: Composition (atomic, composed), and domain of applicability (generic, specific). It is known that the generic-specific dimension has been considered before; however, in this thesis we have included a new dimension atomic-composed. These both dimensions are not exclusively, can be applied at the same time, and are context dependant. One of the models studied in this study, providing a sectors’ network view is the Holon model. This model as well makes use of the fact that natural language can be used to represent the economic and social context. It has three main propositions: 1. Holons could be considered as nodes in a network 2. A holon is composed of four layers: est, vivit, sensit, intelligit 3. Each holon can interact with other holons in their same aggregation level (left & right), not only with the holons in other levels of the hierarchy/holarchy (up & down) Interaction with other holons in the same aggregation level is a proposition presented in this thesis. The original concept of holon (proposed by Arthur Koestler) implies that holons form a hierarchical structure (called holarchy), keeping relations with other holons in upper and lower levels of the hierarchy it is part of. This thesis includes as well, an application of graph theory to get insights about the set of data obtained. In this direction, we identified the most common functions in between all the models assessed by doing an exercise of a graph representation. Furthermore, after studying functions and the Holon concept, we propose some new questions for the complex networks and graph theory community: 1. Going from nodes to holons 2. Consider holons being four-tiered structures. 3. Holons looking up and down to other aggregation levels, but also looking left & right within its own aggregation level. From two-tiered graphs to four tiered graphs, the est layer being the foundation of three overlays: vivit, sensit, intelligit. Currently, the flows that traverse the envisaged sensit and intelligit layer are performed by human beings. In the Telecom sector the est and vivit layer are mainly performed by systems. 4. To open a holon and look inside them, how their internal behaviour is reflected to other nodes in the network/hierarchy. Opening a holon shows another four tiered network. The research methodology described in this thesis proved to be suitable to obtain a functional model. The answer to this “how” question was given via the following steps: 1. Selecting sector specific standards and models based on the proposed criteria 2. Extracting functions from those models and long-listing them (functional portfolio) 3. Mapping functions to generic (non-telecom sector specific) model (testing) We have obtained a list of functions that was mapped to three selected generic models (STOF, CTOM, Holon) and to the meta-functions (that are common to all sectors). This led to the conclusion that it is possible to derive a novel functional model from the existing models, if we have a focus on a specific target (in our case: to serve the sectors network). The best of breed model we have chosen is based on the Holon concept explained above.