Upon gaining independence from the USSR in 1991, Ukraine inherited an analog PSTN telephone system that was antiquated, inefficient, and in many places in disrepair; meanwhile demand overwhelmed the supply with more than 3.5 million households applications for telephone lines pending. Telephone density has since risen and the domestic trunk system is being improved; about one-third of Ukraine's networks are digital, and the majority of regional centers now have digital switching stations. Improvements in local networks and local exchanges continue to lag.