* Firm proposes concessions to regulators
* Details not disclosed
* European Commission has concerns about deal
* Commission to rule by May 30
BRUSSELS, March 12 (Reuters) - Syniverse Technologies has offered to make concessions to European Union authorities as it seeks approval for its 550-million-euro ($716 million) offer for rival mobile roaming firm Mach, EU antitrust regulators said on Tuesday.
U.S. firm Syniverse proposed concessions on Monday, the EU competition authority said on its website, without giving further details.
Companies typically offer to sell parts of their business to ease worries about their market clout after a takeover.
Syniverse’s offer came shortly after the European Commission spelled out its concerns about a merger that would create the world’s biggest data clearing house for mobile roaming services.
The Commission opened a wider investigation into the deal in December and aims to whether or not to approve it by May 30.
In December, the competition watchdog said that the combined company would dwarf its competitors, making customers more vulnerable to price increases.
Syniverse, owned by private equity firm The Carlyle Group , and Mach, which is controlled by Warburg Pincus, collect customers’ roaming data which mobile providers use to determine payments they make to each other for roaming services.
Mach’s customers include France Telecom subsidiary Orange, Spain’s Telefonica, Deutsche Telekom unit T-Mobile, U.S. mobile phone operator Verizon Communications’ joint venture Verizon Wireless, Microsoft and Dutch airline KLM.