Ericsson Radio Systems AB was the name of a wholly owned subsidiary in the Ericsson sphere, founded January 1, 1983 by buying out all former owners of (SRA). The company was well known in Scandinavia and elsewhere in the 1980s, as it was deploying NMT systems and developing a line of mobile telephones under the brand name Hotline. In 2002 the subsidiary changed its name to simply Ericsson AB and absorbed 19 other legal entities in the Ericsson sphere, but kept its company registration number with the Swedish state, so it is still the same legal entity as Ericsson Radio Systems. The merge of the smaller legal entities was done to cut down operating costs. The main activity within Ericsson AB is infrastructure for mobile telephony.