Secret phone calls and security snafus: Sibling rivalry meets the home network.All this talk about spyware and phishers bringing you down? Learn what to do when security, misapplied, kills your computer and inexpensive ways to play spymaster with encrypted voice calls.

Marie from Atlanta: Our older daughter wants to keep her little sister from listening to her phone conversations. Does VoIP provide encryption to keep conversations secret?

Coach: VoIP providers like Vonage and AT&T CallVantage don't, no. But remember, conversations have to connect to traditional telephone lines to reach people who aren't using VoIP, so any encryption would have to be decoded at the VoIP-landline connection point, anyway. Besides, providers eventually will fall under the federal wiretap access laws, making encryption a no-no.

But Skype Technologies, which lets you make free voice calls between PCs, encrypts voice connections. Your older daughter and up to 50 of her paranoid co-conspirators will need a headset to connect to their PCs, but once they download the Skype client software, they can talk over 256-bit encrypted connections.

Phil from outside Chicago: I recommended my neighbors sign up for VoIP, but now they're mad because none of their extensions work.

Coach: The easiest way to regain the convenience of extensions is to buy new cordless phones that are "expandable" and support multiple handsets from vendors such as Motorola, Panasonic, General Electric, AT&T, Uniden and others.

Some support up to eight handsets. Office warehouse stores and online retailers have models you can buy with two handsets for about $100. Extension handsets tend to be in the $40 to $50 range each.

Readers in the Northeast have another option - Optimum Voice . Owned by Cablevision, Optimum Voice installs the broadband phone router at the telephone company demarcation point. This runs the broadband phone connection over the installed home phone wiring by plugging the start of the house phone wiring into the VoIP router or telephone adapter, so your extensions work.