HP has bought mobile software developer Bitfone for an undisclosed sum.

HP said it will use Bitfone's technology to help business customers manage the cost and security of mobile IT deployments. It is the third acquisition by HP in recent months. The company closed its $4.5 billion purchase of Mercury Interactive in November, and announced in September it would buy VoodooPC, a high-end PC gaming vendor.

Bitfone's products include mProve, an application used by handheld device makers to upgrade software on mobile devices remotely, and FusionDM, a server-based software tool that enables wireless operators to manage their subscribers' accounts. Bitfone customers include wireless operators such as T-Mobile and SK Telecom, semiconductor makers like Freescale and Qualcomm, and handheld manufacturers including Motorola and Samsung.

Some of Bitfone's customers make devices that compete with HP's iPAQ handheld, but HP did not say whether it planned to continue selling them software after the acquisition. Other handheld manufacturers currently using Bitfone software include Palm, Kyocera, LG Electronics and Sony Ericsson, among others. HP's iPAQ devices use Microsoft's Windows Mobile OS to provide phone service, mobile email, GPS and digital photography.

Bitfone's 134 employees will be added to HP's personal systems group.