He added that it presents a small bill, ranging from $4 to $8 per month. CallWaves provisioning and billing relationships with telcos allows its fee to appear as an additional charge on the subscribers local Verizon, etc., bill. The $4 Messenger service includes the caller-ID applet, a virtual inbound fax number and the ability to hear voice mail. The $8 service, called CallWave-Connect, includes real-time ad hoc or preconfigured call forwarding to any number. The company, which so far has sold through inexpensive, online channels, has reseller agreements with ISPs, including Earthlink. And though the IP calls theoretically can be routed to a SIP (Session Initiation Protocol) phone, their typical customer doesnt have such things. Nor does he want to use a microphone and speakers. "Our approach to VOIP is shaped for the nontechnical user. To do that, you have to stay hardware-independent," Hofstatter said.Click here for a column on a mobility and messaging add-on for the small-biz PBX.And although they absorb a variable cost for completing calls across Level 3s network, they claim to realize an almost 90 percent gross margin on their service, because their subscribers take far fewer of their incoming calls when they can see the "enriched" caller ID. The service comes with a "Telezapper"-type feature that screens out telemarketer calls based on heuristics and automatically deletes the subscribers number from the telemarketers autodialer. Today, with more than 840,000 subscribers in 50 states, CallWave began in 1999 with a free, advertising-supported service named Internet Answering Machine. As an answer to the then-widespread problem of phone lines tied up on dial-up Internet connections, it simply answered incoming phone calls that hit the subscribers busy signal. Via PC applet, it presented and recorded the voice mail in real time, as the caller left it. Faced with declining ad revenues in 2001, CallWave moved to a paid-subscription model. It added call control to its applet in 2003, allowing users to pluck callers out of voice mail and automatically forwarding calls over the PSTN to cell phones or other lines. This month, it added VOIP transport with the Level 3 agreement. The company also issued an initial public offering on Sept. 30, under the trading symbol CALL. Check out eWEEK.coms for the latest news, views and analysis on voice over IP and telephony.