BARCELONA (AFP) - The ranks of cell phone subscribers will swell to five billion people this year thanks to the growth of smartphones in developed nations and mobile services in poor nations, a UN agency said Monday. The International Telecommunication Union (ITU) also said the number of mobile broadband subscriptions would exceed one billion this year after reaching 600 million in 2009. Even during an economic crisis, we have seen no drop in the demand for communications services, ITU Secretary-General Hamadoun Toure said in a statement at the Mobile World Congress in Barcelona, Spain, the industrys biggest trade show. The number of mobile subscribers had reached 4.6 billion people last year. I am confident that we will continue to see a rapid uptake in mobile cellular services in particular in 2010, with many more people using their phones to access the Internet, Toure said In the developing world, the growth has been driven by the use of phones for mobile banking and health services, the ITU said. Good examples include sending reminder messages to patients phones when they have a medical appointment, or need a pre-natal check-up, Toure said. Or using SMS messages to deliver instructions on when and how to take complex medication such as anti-retrovirals or vaccines, he said, adding that such uses can save millions of dollars and lives. People with no bank accounts but mobile subscriptions are also increasingly able to do financial transactions with their phones in developing countries, he said.