With cost-saving voice over Internet telephony taking off and replacing wired phones, makers of cellular phones are taking notice. Cell phone heavyweights Qualcomm, Texas Instruments, Nortel Networks and others are <A HREF="http://news.zdnet.com/2100-1035_22-5618191.html?tag=zdnn.alert">incorporating VoIP into the cell phones,</A> chips and wireless network equipment they manufacture or design. VoIP is the basis for Internet phone services, popularized by commercial VoIP provider Vonage and free peer-to-peer phone service provider Skype.