Can cellphone app send/receive data like old dialup phone modem?

Question

I remember that
old modems used phone lines to transfer internet data.

I'm aware that it would be expensive (see edit notes below) and most mobile phones have cellular internet.

But here's my question:
How Can i transfer internet data over mobile phone "call line" without additional hardware?

EDIT: I'd like to transfer data via voice channel.

I made some calculations and the results are that transfer at 56Kbits per second would be 20 times more expensive then using internet provided by cell company.

Answer 1

The answer if its possible is:
-probably yes for android and
-no for iOS

Here is a video for acoustic modem using speaker and mic http://www.youtube.com/watch?v=bLRK51_1L2k

I guess it would be possible to make Android app that would receive call and demodulate incoming data.

As for the iOS - the problem is in their Terms Of Service.
Because Apple don't want anybody to record phone calls (to obey the anti wire-tapping laws), it dosn't allow to forward call to app.