Linksys Dual-Mode Internet Telephony Kit. Interface: USB 1.1. Frequency band: 1.88-1.9 GHz. Bundled software: Skype. Base dimensions: 118 x 125 x 63 mm, Handset dimensions: 47.37 x 132 x 34.62 mm, Handset weight: 130 g. Compatible operating systems: Windows XP / 2000, Minimum system requirements: CD-ROM Internet, Minimum RAM: 128 MB