Cisco brought more clarity to its VoIP product line - literally - this week with the acquisition of SignalWorks, a maker of software for improving the sound quality of IP phone conversations. SAN JOSE - Cisco brought more clarity to its VoIP product line - literally - this week with the acquisition of SignalWorks, a maker of software for improving the sound quality of IP phone conversations.In its second acquisition this year, Cisco will exchange $13.5 million in stock for all outstanding shares of SignalWorks, of Mountain View, Calif. Pending approval from both companies, the acquisition is expected to close in the fourth quarter of Cisco's fiscal year, which ends in July.Cisco plans to integrate SignalWorks' Acoustic Echo Canceller (AEC) voice processing software into its line if IP phones and softphones. The software includes algorithms for improving voice sound quality, as well as adding such features as multiple microphone support and stereo sound to IP telephony calls. Cisco says some of its VoIP customers have already deployed the SignalWorks AEC on Cisco IP phones as add-on software.SignalWorks engineers and other employees will report to Don Proctor, vice president and general manager of Cisco's Voice Technology Group.Cisco was the leader in IP phone shipments, with 50% of the 1 million units shipped last year, according to Synergy Research Group. Major competitors to Cisco in the IP phone and PBX market include 3Com, Alcatel, Avaya, Nortel, NEC Mitel, and Shorelien, as well as phone-makers Pingtel, Polycom.