There’s have been quite a few ways to use your iPhone as a Modem. Earlier methods were cumbersome and too complex for normal users.
Then came an easier way, an app called NetShare was launched which made things very easy.
I had also posted a Tutorial to Use your iPhone as Modem via the NetShare Application.
But NetShare was not a free application. An alternative to NetShare has just been released and is now available via Cydia !
The Application is named simply as “iPhone Modem” and promises to tether your iPhone within just 10 seconds !
I haven’t personally tried it yet, but from what I heard it works just as advertised and easy to use !
Get it now from Cydia.
About those wondering what Cydia is, Cydia is a AppStore like Application. You need to JailBreak your iPhone.

October 13th, 2008 at 7:38 am
I downloaded iPhone Modem: Now what?
Thanks
December 3rd, 2008 at 11:42 pm
I downloaded iPhone Modem: Now what?
December 26th, 2008 at 5:00 pm
It’s not free!!! It cost 9.99
January 13th, 2009 at 12:59 am
I am using iPhone software 2.2 (5G77) and modem firmware 2.28. I can’t find “iPhone Modem” or “NetShare” in Apple Store on my iPhone. Can someone send some detail over. thank you so much.
March 15th, 2009 at 4:10 am
thax
March 18th, 2009 at 3:07 pm
Sounds cool, iphone working as modem. Will try and hope it works fine.
June 24th, 2009 at 3:42 am
Its not working, I have dowloaded Iphone modem on my Iphone 3g and the helper App on pc . My wlan adopter is not identifying the network and I m not able to open Iphonmodem aap on my iphone , it opens and disapears . Anyone can help
August 5th, 2009 at 1:34 pm
top free download application store
August 18th, 2009 at 5:40 pm
I m using it. It’s cool but u need to buy registration keys otherwse it’s frustrating