## 2 State of the Art in Telecommunications Infrastructures and Services Sustainability  
Incumbent operators in developing countries are usually reluctant to deploy rural telecommunications infrastructures in sparsely populated areas far from cities. The case for mobile cellular networks clearly illustrates the dynamics of the market: a MNO (Mobile Network Operator) needs to invest a great deal of money and effort in order to reach many small villages over a large area, while the expected revenue is very low. Moreover, many governments leave MNOs free to decide whether they will start providing their services in small villages, but once they provide connectivity they are forced to stay; this is the case for Peru and explains why operators don't provide any connectivity at all over large remote rural areas.  
Under those circumstances, many researchers and experts in ICT4D (Information and Communications Technologies for Development) are trying to find new paradigms for connecting the unconnected and for providing services to underserved communities. a variety of the different approaches is explained in a taxonomy of \"alternative networks\" proposed in [1]. In the first decade of the XXI century, some alternative telecommunications networks were pushed by technological groups that were sensitive to the reality of unconnected remote areas; these pilots showed, firstly, the technical difficulties of deploying low-cost infrastructures over regions that lack electricity, access to existing supporting structures for telecommunications equipment, technical staff for maintenance, etc. Clear examples are the first telemedicine networks promoted by our consortia in Latin America [2; 3], experiences promoted by KTH in Africa [4], or networks deployed by the TIER group in Asia [5], among others. Some of the most persistent groups investigated how to make those pilots sustainable and went beyond the technical issues, proposing appropriate maintenance models that took into account the hazardous conditions of telecommunications infrastructures in remote, underserved rural areas; the TIER group [5] and the EHAS group [6] are only two examples among many others.  
In a second stage, interdisciplinary groups focused on aspects such as management and real, long-term sustainability of rural telecommunication infrastructures in remote regions [7; 8; 9]. The relevance of the participation of local communities as fundamental actors in all the stages of ICT4D projects becomes more and more important [4; 7; 10], and some research certainly points to the Community Networks paradigm [1] being the way to promote integrally sustainable and appropriate telecommunications solutions for rural communities. Relevant examples of this trend can be seen around Zenzeleni networks in South Africa [9], Rizhomatica in Mexico [11], and the bottom-up community cellular network in Papua presented in Reference [10].  
However, from the \"technical\", top-down initiatives to more recent, bottom-up successful experiences, the big telecommunications operators have been seen as difficult partners from the point of view of all other stakeholders, as they are very powerful and have clear market-driven dynamics. The TUCAN3 Gproject, funded by the European Commission, tried to fill this gap in the quest for solutions to connect the unconnected, and successfully deployed pilots of 3G cellular networks in remote areas involving an MNO [12; 13]. TUCAN3G marked the guidelines for making alliances with different stakeholders that seek more sustainable and scalable rural telecommunications networks with the participation of an MNO, an experience that should be seen as complementary to the also successful experiences of bottom-up initiatives with a strong emphasis on the role of communities.