India's Aircel carrier begins selling iPhone 3GS with annual data plan for $236

The new offer, which Aircel promotes as "unbelievable," supplies either "unlimited" 3G data (tethered from 3.6 Mbps to a rather slow 128Kbps after a fairly reasonable 2GB monthly data use) or a 2G plan that includes unlimited 2G data, 1000 minutes of talk and 2500 SMS per month.

The new prepaid option is somewhat comparable to a new prepaid plan available in the US, tied to the brand new 16GB iPhone 4S or 8GB iPhone 4. Cricket Wireless began offering the two models in the US in June for $500 and $400, respectively, with a $55 per month "unlimited" plan that also slows down after 2.3GB of use.

In the US, iPhone plans have largely remained identical over the last five years even as new carriers Verizon and Sprint have partnered with Apple to sell the phone. Outside, however, carriers in other countries have tried different plans.

In some countries, including Japan, subscribers pay full price for iPhone hardware but pay it off in monthly installments as they use it, in addition to their lower service plan fees.

In other markets, carrier subsidies are much lower, allowing cheaper smartphones to offer a greater price gap, undercutting the more premium-priced iPhone options available.

Apple continues to experiment with its carrier plans, particularly in cheaper prepaid plans like those now being offered by Aircel in India and Cricket in the US.

Sprint's prepaid subsidiaries Virgin Mobile and Boost Mobile were both rumored to soon begin offering a similar plans to Cricket.

Within the last quarter, Apple has also added eight new regional US carriers offering slightly cheaper, conventional post-paid plans, including nTelos, Alaska Communications, GCI, Appalachian Wireless and Cellcom in April and Kentucky's Bluegrass Cellular, California's Golden State Cellular, and Kansas' Nex-Tech Wireless in May.