My Net Fone said the acquisition will give it a "carrier grade global voice network" spanning four continents, specialist staff, custom-built international voice trading systems, over 220 international carrier relationships and interconnect agreements and the Telecom New Zealand International brand.
The purchase will give it an incremental 2.8 billion minutes a year, and a global wholesale customer base of 220.
It also will have a three-year contract with Spark to provide international minutes which it says is worth about A$10 million a year in sales.
The Australian company described the deal "as a huge step up" that will transform it "into a significant player in the global market."
My Net Fone will initially fund the transaction via an A$25 million bank facility.
Its shares last traded on the ASX at A$3.01 and have gained 44 per cent in the past 12 months.
Spark rose 0.7 per cent to $3.09 and has advanced 26 percent in the past year.