As voice over IP (VoIP) equipment and services drop in price and improve in performance and functionality, the technology becomes more attractive to small and midsize businesses. At the same time, VoIP vendors are targeting the SMB market, which has lagged other market segments due primarily to the difficulty these businesses have in finding and purchasing the right VoIP solution for them, according to analysts. Nortel pioneered VoIP services for small businesses with its introduction in 2005 of the Business Communications Manager 50 IP telephony system, which offered a way for customers to migrate to VoIP from their existing analog and digital phones. BCM 50 is a closed system, however, and Nortel isnt expected to sell VoIP systems based on the Session Initiation Protocol standard. Digiums Asterisk, SipFoundrys sipX, and other open-source IP PBX solutions let customers use nearly any client device and application platform. Asterisks Web-based management and user call-control tools have won the support of third-party companies, businesses, and educational users by offering improved performance and call quality. VoIP provider ShoreTel is slowly supporting SIP in its client devices, and SIP support is expected to be improved in the companys future products. While such large networking companies as Cisco Systems and Nortel offer VoIP systems for small businesses either directly or through VARs, smaller vendors such as D-Link and Linksys now sell VoIP products to small businesses as well.