Internet phone questions answered

Q: How does Voice over Internet telephony work? What makes it different from traditional phone service?

A: Traditionally, a phone conversation is converted into electronic signals that traverse an elaborate network of switches in a dedicated circuit that lasts the duration of the call.

In Voice over Internet protocol, a conversation is converted to packets of data that flit all over the Internet or private networks, just like e-mails or Web pages, though voice packets get priority status. The packets are reassembled and converted to sound at the other end of the call.

Q: Is the system as reliable as the old-fashioned network?

A: Early VoIP services sounded tinny, delayed or digitized. In recent years, the technology has gotten much better, and Guzman &Co. analyst Pat Comack said it won’t be long before it achieves the tech industry’s vaunted "five 9s" level — 99.999 percent reliability.

Even free services such as Skype, launched by the people behind the music-sharing site Kazaa, now can create clear connections. For now, VoIP may not be perfect, but cell phones have made people more accepting of less-than-ideal phone calls.

Q: What kind of equipment do I need?

A: A broadband Internet connection. You can use a regular phone, as long as you connect it to an adapter.

However, companies such as Cisco Systems Inc. now make VoIP phones that don’t require adapters. The adapter or new VoIP phone connects to a broadband modem. Some VoIP providers can link to an entire home’s wiring so adapters aren’t required at each extension.

Q: What are the advantages of VoIP?

A: It can make long-distance calls less expensive by removing some of the access charges required for use of the public telephone network.

A user’s physical location also becomes irrelevant; the VoIP company Vonage lets people in Illinois have New York area codes or vice versa, if they want. VoIP also can power videoconferencing services, or lead to specialized new applications such as checking voice mail from a Web page or programming call-forwarding so calls from work get routed to voice mail while calls from your sweetheart go to your cell phone.

Q: What are the disadvantages?

A: Some VoIP services don’t work in blackouts or connect seamlessly to the nearest 911 dispatch centers.

In some cases, DSL subscribers can’t use it as a primary phone line because they would lose the DSL if they cut off traditional local phone service. Plus, traffic on today’s Internet can be slowed by worms, viruses and other attacks.