Silicon Laboratories SI2493/57/34/15/04 - Manual (Page 212)

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7.6.4.3. Speakerphone Transition
A SP Button On Event will trigger the transition to Speakerphone system voice mode. Based upon the point at
which the event is received, the voice driver will vector to a user answer state to gracefully exit the TAM PSTN
mode.
7.6.4.4. Handset Transition
A Handset Raised Event will trigger the transition to Handset system voice mode. Based upon the point at which
the event is received, the voice driver will vector to a user answer state to gracefully exit the TAM PSTN mode.
7.7. Speakerphone
7.7.1. Overview
The Si2494/39 speakerphone consists of the following function components as shown in Figure 29 on page 188:
 Acoustical echo canceller (AEC)
 Acoustical echo suppressor (AES)
 AEC double-talk detector (DTD)
 Line echo canceller (LEC)
 Howling controller (HC)
 High-pass filter (HPF)
7.7.2. Simplex Speakerphone
Simplex Speakerphone (SSP) is a special case of speakerphone operation. Like Speakerphone, it allows two-way
hands-free voice communication over a telephone line, but SSP allows communication in only one direction at a
time. The direction of voice transmission can be done automatically, based on the presence of local and remote
speech at the modem, or manually using a push-to-talk function. Simplex and full-duplex speakerphone modes are
mutually exclusive. SSP supports the Ademco Contact ID and SIA security protocols. It also supports DTMF
generation and detection. DTMF detection is enabled only during +VTR. Commonality in control registers between
SSP and full duplex facilitates programming across platforms. SSP supports Type II Caller ID, but Caller ID is
disabled during +VRX. A DLE<R> event report is sent to the DTE when a SAS Call Waiting tone is detected. If a
CAS tone is detected, the modem mutes the Si3000 speaker while Caller ID Type II data are being captured. It
then reports Caller ID info to the DTE as a DLE-shielded complex event. This happens automatically, without the
need for an AT+VCIDR? command.
1. The microphone sample is taken after U19D; the speaker sample is taken after U19C. However, the scale
factors are set to 1.0 internally, so U19C and U19D will not affect the SSP.
2. To mute the local talker, set U199 [1] to 1 and MUTE_DAA_TO_MIXER=1. To mute the remote talker, set
U199 [3] to 1 and MUTE_MIXER_TO_DAA to 1.
AT+VTS=[500,0,100] OK Play special administrator tone.
[Playback Menu Options]
Using the +VTX command, the voice driver
can playback a menu and monitor DTMF
digit events to perform operations
remotely.
Table 132. TAM PSTN Interrupted Answer – OGM Playback with DTMF Menu Entry (Continued)
Host to Modem Commands / Data
Modem to Host Result
Codes/Data
Local Modem Actions