Fluke is buying VoIP software maker Visual Networks for $75million.

Visual provides software and applications to help sysadmins manage their network, including capacity planning, problem location and performance data gathering.

In March, it introduced a new suite that measures VoIP performance and optimises networks for VoIP calls by measuring availability, delay, jitter and bandwidth use. The company will be pulled into Fluke - which provides testing, monitoring and analysis products for enterprise and carrier networks.

Fluke president Chris Odell waxed lyrical about the purchase: "The anticipated acquisition of Visual Networks will be a significant step in the evolution of Fluke Networks' Enterprise vision as we continue to position ourselves for leadership in the network and application analysis market.

"We expect to be able to provide increased benefits and capabilities to enterprise customers that manage their own networks or outsource to a managed service provider."

Visual Networks' shares jumped 21 percent on the news.