Communications company GOtalk has bought Telstra's international calling cards business Say G'day and Super Buzz as part of a "logical extension" to its business, says GOtalk CEO Steve Picton.

He estimates the deal will push GOtalk's market share of international phone card users upwards of 50 percent within Australia and New Zealand, and anticipates "incremental market growth" for the future.

The acquisition enables GOtalk to leverage the credibility of the Telstra brands, "which are perceived as quality brands".

Picton said it hopes to tap into the huge loyalty the cards have garnered over the years. Market share and access to existing distribution networks were other factors in its decision to purchase, he added.

Already well positioned, the pricing structure of the cards will not change over the short term. GOtalk's immediate priority is to maintain "the high quality that Telstra has been providing and continuing with the premium rights...which has become a trademark", he said.

"Our entire business by definition is all about micro-marketing," he said, adding that pricing decisions and marketing campaigns will continue to be carefully tailored to specific market segments.

"This is our core strategy which differentiates us from our competitors. We invest millions of dollars on marketing which focuses on the small and large needs of customers in our market".

Picton says customers can expect product enhancements in the future.