> 2 | Overview of Audio Interfaces

> The GSM module comprises three audio interfaces:

> • | A serial digital audio interface (DAI) designed for PCM (Pulse Code Modulation).

> • | Two analog audio interfaces, each with one analog microphone input and one analog speaker output.

> This means you can connect up to three different audio devices, although only one interface can be operated at a time. Using the AT^SAIC command you can switch back and forth between each of the analog interfaces and the digital interface. See also Section 6.2 for details on how to use AT^SAIC.
> The DAI replaces the AD/DA converter unit of the module. Thus, all digital filters, gains and DSP functions are usable via DAI. If a flat frequency response without influence of DSP is required, we recommend audio modes 5 or 6.
> Figure 1: Block diagram of digital and analog interfaces selectable with AT^SAIC