or you just use a so-called turbo sim card that tricks the phone permanently into thinking it's on the ATT network. then you don't need to do any software hacks later on (or be shut down by future updates from apple): http://arstechnica.com/apple/news/2007/08/turbo-sim-add-on-a...
Did you actually RTFA? Or, even the article you posted? From your link: "The unlocking process is still a bit complicated and requires SSH on your iPhone"
So you still have to jailbreak your phone. And really, this article is only tangentially related to jailbreaking. It's about using the iPhone with Skype and a GoPhone plan.
No the article's title is how to use an iphone for 23 bucks a month and not how to use an iphone with skype.
Being able to insert a pay-as-you-go SIM card is front and central to the plan here, or you are forced into a full cellphone plan. That implies either the turbo sim card hack or a soft unlock.
Further, insinuating that i have not read the article or neither the link that i have posted is quite annoying. The topic is not easily answered, because with Firmware upgrades by Apple it's a cat-and-mouse game. Over a longer period, the most quoted solution that I have read about is the Turbo SIM hack.
The Turbo SIM card hack was popular with first generation iPhones (and made big press in previous years; I recall the company Bladox from Czech Rep. was featured a lot). That's about when I read up on this topic. Recently though, it stopped working with the Firmware 2.2, which is when this software hack from Yellow Sn0w worked... with 2.2.1 and beyond soft unlock doesn't work anymore, and it's apparently back to turbo sim - see: http://www.edmartechguide.com/2009/03/research-before-you-up...
For further info, from iPhone Hacks, O'Reilly, April 2009:
Hack 47. Unlock Your iPhone with a SIM Hack
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You can use a locked phone on a different carrier with a physical hack to the SIM card.
As mentioned in Section 45, the second method of the anySIM software hack changed the baseband so that any MCC/MNC pair (used to identify a cell network) portion of the phone's IMSI (International Mobile Subscriber Identity) would appear to be a valid pair. Even if you can't successfully hack the baseband—for instance, on a 3G iPhone—there is a hardware method for doing the same thing.
As there already existed a large market for unlocking phones prior to the iPhone, many companies were already producing solutions for hacking SIM cards. Bladox, a Czech Republic–based SIM test tool manufacturer, introduced the Turbo-SIM in 2004. This clever device consisted of a thin circuit board shaped like a SIM card, and a tiny microcontroller (Figure 7-8). By cutting a tiny square out of the plastic casing of the SIM card (which did not affect the SIM card's normal functioning), the Turbo-SIM could piggyback the SIM card, intercept its communication with the phone, and mediate between the two to make sure they "agreed."
SIM card sandwich hacks of this nature were some of the most consistently effective for first-generation iPhones, and are currently the only effective solutions for iPhone 3G hacking. As with many hacking solutions, a game of cat-and-mouse has ensued, and many of these SIM piggyback cards ceased to work when firmware 2.2 was released for the iPhone. Because the piggyback SIM has a reprogrammable microcontroller, they can be upgraded with new firmware (with the right programming equipment) to work around new problems.
