iPhone 3.5mm jack based application

Question

I want to encode data via a DTMF encoder and send it back to the iPhone via the 3.5mm Jack. Is it possible to send data back into the 3.5mm jack. conventionally audio signals are sent out over the iPhone 3.5mm jack?

Is there provision to deal with DTMF and 3.5mm jack based input applications in Iphone's External Accessory framework?

Answer 1

Yes, it is possible. You have to record input sound and use a DTMF receiver, which nowadays is a trivial and low-CPU task.

In the iPhone Accessory Specification this topic is not covered. However there are far better ways to let accessories communicate with installed apps...