(Telecompaper) Ericsson has admitted a fault in its network software has caused major mobile service outages in "multiple countries". The company said the problem is thought to be due to an expired software certificate and it's taken "immediate action" to minimize impact and support the restoration of services. A "limited number" of its network operator customers were affected, Ericsson said in a statement. These are thought to include O2 UK and Softbank in Japan.