iPhone APP - native versus external

I am contracting a company to develop an iPhone APP.

Here is the issue: part of the APP will deal with signatures that are sent via text message from user to user.

I have been told that the native iphone OS is closed and that can't be modified so the only solution to is to build a completely new SMS APP using tools such as phonegap, or appcellerator, etc.

Is there any way to develop the app that works with the exisitng iPhone SMS program or is it true I need to build a whole new application? The problem wit开发者_如何学Pythonh building a whole new application is the iPhone will have to use an external SMS gateway and charge fees for that.

Also, are there any recommended iPhone developers ?

Thanks

iPhone OS 4 will support In-App SMS:

In-App SMS Compose SMS messages from within apps, similar to the Mail compose sheet added in iPhone SDK 3.0.

If you don't want to use a third-party SMS system, you'll have to wait for iPhone OS 4.

Both PhoneGap and AppAccellerator may be banned from future store submissions- wait until the shakeout from Apple's change in development contract finish up, to see what other possibilites exist if you do not want to use Objective-C to build a custom SMS beforehand...

But I'd wait for 4.0 and implement the features using the system calls there, you can start building today as the beta SDK and iPhone images are out.