At 6 p.m. today, the world’s most famous phone goes on sale at Apple and AT&T (News - Alert) stores. Apple has restricted initial sales of the iPhone to two for each customer, while AT&T is selling just one iPhone per customer.

 

Apple’s Steve Jobs (News - Alert) has said, “The iPhone in 2007 could have an effect on the cell phone industry akin to the effect the Macintosh computer had on the personal computer industry in 1984.”

 

That wouldn’t be surprising, if only because the Apple iPhone (News - Alert) is, in fact a diminutive, portable Macintosh computer, since it runs all of Mac OS X, which means it also supports multitasking, networking, security, and desktop Mac applications.  Unlike a conventional Mac computer, however, the iPhone is only 11.6 millimeters thick and is equipped with a 2 megapixel digital camera, a 3.5-inch screen, and a different set of interfaces, including one based on “Multitouch” technology (a highfalutin’ kind of touchscreen), which takes the place of a conventional keyboard or stylus.  The IPhone syncs up your personal data (media, through iTunes), contact information, email accounts, calendars, notes, photos, and bookmarks.

 

AT&T has exclusive rights to market iPhones for five years.  However, Apple has taken responsibility for iPhone activiation, along with account maintenance via its iTunes software that runs on a customer’s Mac or PC.

 

Glowing reviews of the iPhone have appeared in the New York Times, Washington Post, and elsewhere.  Generally, however, such positive reviews inevitably make mention of the fact that the iPhone’s connection to the Internet would be via AT&T’s relatively slow EDGE network.

 

 

EDGE’s origins began with GSM (Global System for Mobile communications, originally Groupe Spécial Mobile) the world’s most popular mobile phone standard, used by more than two billion people.  GSM sits between early analog 1G wireless phone technologies and modern 3G mobile services.

 

At some point, carriers decided to improve the GSM realm by offering a higher bandwidth for data than earlier wireless networks, but less than 3G networks.  Thus, 2.5G networks appeared, promoted by carriers as a migration path to eventual 3G deployments. 2.5G wireless networks introduced packet-switched data services that conserve bandwidth, even though they’re “always on,” which means that when you use a data service over 2.5G, you only occupy bandwidth when you actually send and receive packets.  2.5G voice calls, however, are circuit-switched and consume a constant bandwidth.

 

On the GSM path to 3G, the ability to send packets over GSM circuit-switched voice channels was enhanced with a technology called HSCSD (High Speed Circuit Switched Data).  An even more powerful technology came along, however, called GPRS (General Packet Radio Service), a GSM-based packet data protocol that can be configured to consume all eight timeslots that exist in a GSM channel.  GPRS supports a 115 Kbps data rate, though 50-60 Kbps is more likely in practice, especially since the packets must contend for the same bandwidth as GSM circuit-switched voice, and providers will tweak the bandwidth based on the number of subscribers that can be attached as they try to find a profitable mix of users vs. bandwidth-per-user.

 

The GPRS equivalent in the CDMA world is cdma2000 1XRTT, which can both assign more of its 1.2 MHz radio channel per user as well as using a more sophisticated modulation scheme to boost bandwidth for individual users up to 144 Kbps (bursting at 153.6 kbps, and perhaps up to 307 Kbps with advanced technology).  It also involves a new phone and demands a change to some of the base station equipment, doubling voice network capacity and allowing data to be packetized and sent without the need for a traditional circuit to be established.

 

As for GPRS, it can be further upgraded to use the modulation technique called EDGE, which stands for Enhanced Data-rates for GSM (or Global) Evolution.  Officially known as UWC-136 (USA TIA TR-45.3), this builds upon GPRS, allowing GSM operators to use existing GSM radio bands to increase the data rates within GPRS’ 200 kHz carrier bandwidth to a theoretical maximum of 384 Kbps, with a bit-rate of 48 Kbps per timeslot and up to 69.2 Kbps per timeslot when operating under favorable radio conditions.  Although EDGE’s theoretical maximum bandwidth is 384 Kbps, most GSM operators and customers will be pushing wireless multimedia IP-based services and applications at data rates of only about 100-120 Kbps.

 

Some experts call EDGE “a 3G data network running on a 2G voice network,” while other people amusingly refer to it as 2.75G wireless. EDGE is okay for some Mobile Internet services, such as watching movie previews, and sending multimedia messages such as digital postcards with video attachments, though it doesn’t support anything really spectacular.

 

In an interview quoted in the New York Times, Randall L. Stephenson, the new AT&T CEO, said that the fact that the iPhone offers faster WiFi networking would more than make up for the relatively slow pace of its cellular EDGE data network.

 

Apple was probably forced by the fact that true 3G networks aren’t available everywhere, as opposed to EDGE, along with the fact that 3G chips use more power and would decrease the iPhone’s time between battery recharges to an unacceptable interval. Moreover, AT&T has lavished $16 billion to fortify its network over the last two years to handle the expected flood of wireless data users, particularly iPhone users.

 

Once day, however, Yours Truly is sure that you’ll be able to buy an iPhone based on AT&T’s faster network based on HSDPA (High-Speed Downlink Packet Access) technology.  Also known as High-Speed Downlink Protocol Access, HSDPA provides a migration path for 3G wireless networks to boost data bandwidths and capacity.  Current HSDPA deployments in various countries now support downlink speeds of 1.8 Mbps, 3.6 Mbps (currently quite popular), 7.2 Mbps and 14.4 Mbps.  On the horizon is the even more amazing HSPA Evolved, which will initially provide 42 Mbps downlink speeds.