(Adds details about business, comment from analyst)
ZURICH, Dec 19 (Reuters) - Switzerland's biggest telecoms group Swisscom is expanding deeper into user data by buying the rest of an online directories business it does not already own from media company Tamedia for about 220 million Swiss francs ($222 million).
Announcing the deal on Wednesday, state-controlled Swisscom said the purchase of Tamedia's 31 percent holding in Swisscom Directories will have no impact on net debt, adding the deal was already accounted for on its balance sheet.
The acquisition makes Swisscom the sole owner of an operation that maintains address, telephone and contact databases across Switzerland.
Swisscom Directories operates the nation's biggest directory platforms called local.ch and search.ch and offers web design, online advertising, online booking systems and customer relationship management services to largely small and medium-sized Swiss companies seeking to acquire and engage customers, according to its website.
"Swisscom... is the better owner than Tamedia for a business whose model is based on address listings," Andreas Mueller, an analyst at Zuercher Kantonalbank, said in a note to investors, adding the deal had been expected after Swisscom in 2015 gained the right to buy the Tamedia stake when they merged two online search businesses.
Tamedia's other businesses include Tages-Anzeiger, one of Switzerland's biggest daily newspapers.
The deal is due to be completed in the first quarter of 2019, said Swisscom, which is just over 50 percent owned by the Swiss government.
Swisscom shares were up 0.6 percent at 0830 GMT. ($1 = 0.9924 Swiss francs) (Reporting by John Miller, editing by Tassilo Hummel and Susan Fenton)