While the NSA supposedly received records from three largest phone companies, the agency doesn't have the wherewithal to contact smaller VoIP vendors, which has prompted some consumers to switch to other carriers.

Web-based VoIP companies such as Skype offer greater anonymity since PC to PC calls are more difficult to track, and since customers only have to provide an email address to get an account. I'm not sure what records Skype keeps of PC to phone calls, and for how long, but it likely is not as detailed as telco records. Ditto for voice calls between IM clients. New encryption utilities such as Zfone also make it more difficult to intercept communications.

Source: MarketingShift