> 3.7.1 | Supported Audio Modes

> The audio interface can be configured by AT commands. Refer to [1] for details.
> The electrical characteristics of the voiceband part vary with the audio mode. Specifications are listed in Table 11. To suit several types of audio equipment, three audio modes given by default can be selected by the AT command AT^SNFS.
> Regarding audio performance, compliance with the TS 51010-1 specification and GCF recommendations has been certified for the parameters provided by audio mode 1 and audio interface 1. The settings are optimized for the reference handset (type Votronic) connected to the TC65 Terminal (see Section 6.1 and Chapter 7). To ensure that the reference parameters are always within the limits demanded by the standards they cannot be changed by AT command. Furthermore, the reference parameters are set as factory default.
> In audio mode 4 and 5, the gain in the microphone, earpiece and the sidetone path can be adjusted from the cellular device application by using further AT commands.
> Please note that the 2 nd audio interface of the TC65 module is not connected in the TC65 Terminal. Audio modes 2, 3 and 6 can be selected by setting AT^SAIC=2,1,1, for further details refer to [1].

> Table 11: | Audio modes

> Mode No AT^SNFS= | 1 (Default settings, not adjustable) | 4 | 5
> Name | Default Handset | User Handset | Plain Codec 1
> Purpose | Recommended handset | User provided handset | Direct access to speech coder
> Gains programmable via AT command | NO | YES | YES
> Sidetone | YES | YES | YES
> Volume control | NO | YES | YES
> Echo control (send) | Cancellation and suppression | Cancellation and suppression | NO
> Noise suppression | YES | YES | NO
> MIC input signal for 0dBm0 @ 1024 Hz (at default gain settings) | 12.5 mV | 12.5 mV | 400 mV
> Earpiece output signal in mV eff. @ 0dBm0, 1024 Hz, no load (at default gain settings); @ 3.14 dBm0 | 475 mV | 475 mV (default @ max volume) | 1.5 V 6.0 Vpp
> Sidetone gain (at default settings) | 24.9 dB | 24.9 dB | -• dB