The increase in the number of people subscribed to mobile services in Africa to 557 million at the end of 2015 is posing a challenge for the mobile industry, according to a new GSMA report released during the GSMA Mobile 360 Africa conference in Tanzania.

The newly released GSMA Mobile Economy Africa report found that 46% of the continent's population are now mobile subscribers, although the regions remains the least penetrated in the world.

Diego Gutierrez, CEO of Tigo Tanzania says the growing number of mobile subscribers has resulted in a consequent need to invest in infrastructure particularly in rural communities.

"Internet access is still a challenge because not every part of the country has access to data but this is something that operators have been focusing on over the last couple of years with investments in expanding 3G networks and now for example by launching 4G and other ISP technology. That goes along with smartphone technology because providing devices needs to go along with providing reliable internet connections where people can access it from. Its is a difficult task but we have made progress especially here in Tanzania, where competition is also improving and that has led to the rollout of internet connectivity to more rural areas."

A third of all mobile subscribers on the continent are found in Nigeria, South Africa and Egypt according to the GSMA report which also revealed that mobile broadband (3G/4G) accounted for just over a quarter of the total number of connections although this is expected to rise to two-thirds by 2020.

Mortimer Hope, Director of Government & Regulatory Affairs at the GSMA says although there are now 72 live 4G networks in 32 countries across Africa, more investment is needed.

"We need more connections in the other countries and when that happens the percentage that the three countries make up will drop. South Africa and Egypt are more middle income countries so you have more uptake of the services. Nigeria is just numbers. Many of the other countries have fifty percent or less and the total for the continent is now 46 percent. The networks are available in urban areas and large population centres and you've got good network coverage there but as we go to the rural and underserved areas you don't have good network and that is an area we need to work on as industry and government. We need to work together to bridge that digital divide."

The GSMA report predicts that the number of subscribers will triple over the next five years, rising from 226 million in 2015 to 720 million (54% of the population) by 2020.

This rate of growth is insufficient according to Hope.

"We should be doing much more. The global average is over sixty percent. We should not celebrate mediocrity. If you are below the global aberdare then we need to do more. There are two issues with low penetration. One is that there are areas where there is just no network available so it is difficult or costly to get the people in those areas connected. What is of greater concern though is the areas where the network is available but many people are not connected and we have to look at the reasons why they are not connected and some those reasons are affordability and lack of locally relevant content."

The use of mobile technologies and services across Africa generated US$153 billion in economic value last year, equivalent to 6.7% of the region's GDP, according to the same report.

This contribution is expected to increase to US$214 billion by 2020 (7.6% of expected GDP). The report also explains how mobile is powering innovation and entrepreneurship across Africa. It notes that there are now approximately 310 active tech hubs across the region, including 180 accelerators or incubators.