Google is to acquire internet-based calling software firm Gizmo5 to boost its Google Voice service.
Gizmo5's engineers will be joining the Google Voice team to continue improving the Google Voice and Gizmo5 experience, Google said in a blog posting about the deal.
Google Voice provides a variety of services, including multi-device phone numbers and low-cost calling, which has caused some outcry in the US.
The US Federal Communications Commission is conducting an inquiry in response to complaints that Google blocks some calls to save access costs.
Google insists that Google Voice is an internet service and therefore not covered by federal rules that govern phone providers.
But opponents say this is giving Google an unfair advantage over competitors bound by rules that prohibit providers from blocking calls.
The Gizmo5 acquisition is the fourth to be announced by Google this year and comes just days after Google revealed it is to buy AdMob for $750m.