There are some benefits that apply to almost all forms of mobile network sharing . Network-sharing agreements generally benefit operators and the general public from a cost perspective. Network sharing helps operators to attain more efficient coverage, since operators may choose to use only those sites that provide deeper and better coverage, decommissioning sites with poor coverage possibilities. Operators can then reinvest those savings in upgrading their networks and providing better coverage and services to end users.
Passive infrastructure  sharing is usually encouraged. Wireless communication masts and antennas can be unsightly and local communities may object to the construction of new sites because of the visual impact or because of the fear of public exposure to electromagnetic fields around masts and antennas. Site sharing can limit such concerns  and potential negative effects. Another beneficial aspect of site sharing is the amount of energy that can be saved when operators share electrical power, which is often in limited supply in developing countries.
Site sharing can also speed up network deployment and make it less expensive. In the European Union, for example, 2G networks were deployed in the 900 megahertz (MHz) spectrum band, while 3G licenses were assigned in the 1900-2100 MHz band. Because spectrum generally has a shorter range at higher frequencies, 3G networks require more base stations (and therefore more sites) – a significant transition expense for 2G operators. However, if those 2G operators can co-locate 3G equipment on each other’s existing 2G towers, they can enjoy significant savings as a result.
Active mobile infrastructure  sharing may not be permitted under the licensing regimes of some countries. This is the case in India, for example, where the licensing regime for mobile telecommunications does not permit active sharing. Other regulatory agencies may allow active sharing only with strict conditions, in the belief that competing operators should utilize their own infrastructure independently.
Box 6.9: Ofcom’s concerns with infrastructure sharing
“Network sharing could also have undesirable consequences for competition. For example, [mobile network operators] could collaborate on network development and gain information about each other’s costs and plans, which may have a chilling effect on competition in the retail market. Dynamic efficiency may also be lower with fewer networks able to provide high quality mobile broadband services. End-to-end competition, i.e. at both the network and service level, could lead to greater innovation, which could bring significant benefits for consumers. We note that the competition concerns would be amplified if the 900 MHz operators were themselves to decide to share a single UMTS 900 network in response to the actions of their competitors. While it is difficult to quantify the potential impact of these effects, Ofcom’s initial view is that there is a significant risk that both competitive intensity and innovation in mobile broadband services would be weakened, with potentially serious impacts on consumer welfare.”
With the merger of Orange and T-Mobile (Box 2.10) as Everything Everywhere, the number of national mobile operators dropped from 5 to 4 (the others are Telefónica, Vodafone and H3G). To ensure that this number does not drop any further, Ofcom is proposing to structure spectrum auctions to guarantee 4 competing national networks.
Sources: Ofcom, Application of spectrum liberalization and trading to the mobile sector, 20 September, 2007 and
Ofcom’s second consultation on assessment of future mobile competition and proposals for the award of 800 MHz and 2.6 GHz spectrum and related issues, 12 January 2012
Generally speaking, network sharing is a useful tool for regulators and policy makers who want to encourage network deployment in unserved or under-served areas. Several instruments can be used to promote network sharing. National roaming arrangements are probably the most simple and effective arrangements. While roaming leads to a certain level of uniformity among operators’ offerings, this does not necessarily restrict competition significantly. National regulatory authorities that have anti-competitive concerns may allow network sharing for a limited period (for example, one or two years) in order to promote roll-out of initial phases of network deployment. After that, operators could be required to provide coverage using their own networks.
A more complex form of sharing is the mobile virtual network operator (MVNO). The types of MVNO range from resale to bulk buying:
· The resale end of the market buys the existing suite of products and services off the provider at a small discount and resells them under their own name. It is little more than a rebadging exercise and does nothing beyond raising the MVNO's profile in the mobile market segment.
· The true MVNOs buy minutes, texts and data in bulk and provides its own SIM card to its customers. The level of investment required by the true MVNO is much higher - they need to hire a product team and have billing capability for instance - but the rewards are also much greater. They get more control and they should get a better margin.
MVNOs first appeared in Denmark, Hong Kong, Finland and the UK and today exist in over 50 countries, including most of Europe, United States, Canada, Australia and parts of Asia, and account for approximately 10% of all mobile phone subscribers around the world.
 The key reference document for mobile infrastructure sharing is GSR 2008 Mobile Network Sharing, by Camila Borba Lefèvre
 The passive elements of a mobile telecommunications network are the physical components of the radio access network that may not necessarily have to be managed or controlled by the operator after their installation. These elements include electrical or fiber optic cables, masts and pylons, physical space on the ground, towers, roof tops as well as shelter and support cabinets containing power supply, air conditioning, alarm installation and other passive equipment. The assembly of passive equipment in one structure is generally referred to as a ‘site’.
 But, because antennas generally have to be separated from each other by a minimum distance in order to avoid interference, mast sharing usually requires taller (and more visually disruptive) masts. Local planning authorities actually may prefer several small towers to one large one. More discrete (or disguised) structures reduce visual intrusion, but cannot support more than one operator’s antenna.
 The active elements of a wireless network are those elements are managed by operators, such as antennas, antenna systems, transmission systems, channel elements and others.