ce PGPfone, which will offer highly secure service. While all three programs offer essentially the same thing--voice communications--there are significant differences between their features and how each service is packaged.
Internet Phone and DigiPhone systems require 486 PCs running Windows 3.1 or better. The machines must have a Winsock 1.1 interface to the Internet, which may be through a PPP connection to a local Internet service provider (ISP). Connections with America Online or CompuServe are not good enough; your machine must have its own IP address. The packages also require a soun
d card with a microphone and speakers. Low-end sound cards offer only half-duplex communication, where the sound flows in only one direction at a time. Better sound cards can process the signals fast enough to offer full-duplex communication, so both parties can talk at once.
We tested these phone products on a 486 PC with a Sound Blaster card and a PPP connection to a local ISP. This may be the most inefficient setup possible: Voice is turned into a digital message that is immediately converted into an analog audio signal by the modem, then reconverted into a digital message by the ISP. This connection is the norm today, but it will become less common as high-speed digital connections such as ISDN become more available.
PGPfone currently runs only on the Macintosh, but a version for Windows 95 should be available by the time this article appears. We checked out PGPfone on a Mac 6100/60 using the same PPP connection to the same ISP. Internet Phone has announced a Mac version, but it was not avai
lable for testing for this review.
Internet Phone
Internet Phone evolved out of the Internet Relay Chat (IRC) servers that moderated text conversations on the Net. Its architecture is based upon a central server that keeps a list of active users looking for conversations in various topics, but when you actually call someone it's a direct connection, not routed through the server.
You log on to these servers and list your name in the discussion groups you are interested in; other people in a group can see who's on and perhaps give them a call (see the screen above for an example). In other words, you don't need to have someone in mind to use the software. You can just log on and people might call you. Discussion topics range from the sacred (country music) to the profane (sex). As you might expect, many people seemed to be trolling the waters for nothing in particular. If you enjoy speaking with someone you've never met before or talking to people from a different corner of t
he world, then you'll like using Internet Phone. It's like visiting an international bar.
The software itself is well-designed and functional. You can test your microphone's sensitivity (an illuminated graph on the front window tells you if your voice is being accepted), and whether your sound card can handle full-duplex conversation.
Most of our conversations were in half-duplex mode, where the software had to decide which side of the conversation was broadcasting at any time. Internet Phone handles this in two different ways. It automatically senses when the sound rises above a user-set threshold and then opens up your broadcast channel. Sometimes this automatic threshold can become problematic. If you pause, the transmission will click off until you start up again, which can be disconcerting. So Internet Phone also offers a manual option, where you click the transmitter on to speak and off to listen. We usually preferred this mode.
Unlike DigiPhone and PGPfone, Internet Phone offers no
encryption or security features. (A VocalTec representative said the company will incorporate security functions in a future release.) Version 3.1, due for release as this article went to press, includes a new way to interact with some Web browsers so that people can insert hotlinks into Web pages. Click on a link and an Internet Phone call is started.
DigiPhone
DigiPhone is not as much fun out of the box as Internet Phone. There's no central server to tell you who's on-line, so you can't join topics and look for someone to chat with. The software implements a global directory that lets you look up users by some combination of name or location. This is fine if you know someone who is listed, but it's not conducive to making new friends. To make a phone call, you type in the other party's IP address.
The DigiPhone software is more sophisticated than Internet Phone's; it allows you to add new voice-compression and encryption software. The modules that ship with the product ri
ght now aren't particularly strong, though. To use the encryption module, for example, you add a password next to the name of a friend in your personal phone list. If your friend has the same password, then the encryption will work. But the passwords are limited to five characters, so you shouldn't count on much protection. (It will stop your little sister, unless your little sister knows how to program.) Still, this encryption is better than no encryption at all.
DigiPhone allows you to change the sampling rate manually. A slower rate may generate a less accurate digital representation of speech, but it's also less likely to saturate the channel. Lowering this rate is often a good choice because it degrades the sound quality uniformly, whereas saturating the channel leads to missing packets that leave out words, phrases, or even sentences. At press time, Third Planet announced a deluxe version of DigiPhone; it's bundled with a suite of Internet programs and offers extended features, including voice ma
il.
PGPfone
Security is PGPfone's main advantage. Phil Zimmermann is devoted to enhancing the privacy of citizens, and PGPfone's algorithms are probably as good as those used in the secure phones that AT&T sells to the U.S. government. At this writing, there's only a Macintosh beta program (1.0b5), but a Windows 95 version is in development. The system can also operate over an AppleTalk network or a direct-dial line if you want to pay for the call.
PGPfone employs Diffie-Hellman key exchange to create the session key for the conversation. Because this algorithm is vulnerable to a man-in-the-middle attack, in which someone inserts themselves into the data stream, the software provides a short version of the key for you to repeat over the phone line. If you and the person on the other end both see the same phrase on your screens, then no attack is in progress. AT&T's secure phones use the same approach.
You can select either Blowfish or Triple-DES algorithms to encrypt
the bit stream itself. Both have no publicly known weaknesses, and it's illegal to export this software from the United States. The software lets you set encryption parameters and digitization speeds, and it is free for noncommercial use.
In our PGPfone calls, the sound quality was fairly good in half-duplex mode, but quality decreased significantly in full-duplex mode because the number of bad packets skyrocketed.
One Ringy-Dingy, Two Ringy-Dingy
For most people, none of these products can replace the ordinary telephone for everyday use. Most Internet service isn't fast enough or reliable enough yet, though this should change in the next few years. And even accepting this limitation, it's simplistic to pick any one of these products as the absolute best choice.
DigiPhone offers the nicest set of technical features, with its optional encryption and its user-adjustable sampling rate. Plus, it should be easy to incorporate new voice-compression and encryption algorith
ms as they become available in the future.
PGPfone offers similar features as DigiPhone but has much stronger encryption capabilities, as you'd expect. But PGPfone is still only in beta, and as yet only for the Macintosh. In its final form, we expect it will be as good as either of the two commercial products. If you care about security, this is clearly the best choice.
If you're on a private IP network, you may get reliable enough packet movement to get real use out of these products. The rest of the world, especially those looking for entertainment, might want to turn to VocalTec's Internet Phone simply because its chat servers offer a nice diversion.
PRODUCT INFORMATION
DigiPhone.....................$89.95 (dual license)
Third Planet Publishing, Inc.
Dallas, TX
Phone: (214) 733-4790
Fax: (214) 733-4505
E-Mail:
3pp@planeteers.com
Internet:
http://www.planeteers.com/
Circle 1158 on Inquiry Card.
Hey Baby, Call Me at My IP Address
