Silicon Laboratories SI2493/57/34/15/04 - Manual (Page 203)

AN93
Rev. 1.3 203
7.6.2.2. Review OGM
The RS232-to-Si3000 gain register UB8 in the ISOmodem can be used to adjust the voice stream gain. Use the
+VGT command to adjust the UB8 value in command mode. It is best to maintain two versions of +VGT: one for
RS232-to-Si3000 and another for RS232-to-DAA.
7.6.2.3. Record Local ICM
The Record Local ICM is identical to the Record OGM procedure provided in Table 127 on page 202. The main
difference is that one of the ADPCM formats is generally used and the PCM file is stored with the other ICM files
recorded from the PSTN.
7.6.2.4. Review ICM
The Review ICM is identical to the Review OGM procedure provided in Table 128 on page 203. The main
difference is that one of the ADPCM formats is generally used to conserve message space.
7.6.2.5. Speakerphone Transition
The SP Button On Event will trigger this transition. See Table 136 on page 219 for configuration sequence.
7.6.2.6. Handset Transition
The Handset Raised Event will trigger this transition. See Table 120 on page 197 for configuration sequence.
7.6.3. TAM Handset
Using the handset to record the OGM will result in better message quality. The handset can also be used to screen
messages in private. The host will need to correctly process the Handset Raised Event to keep the modem on-
hook during record/review operations.
7.6.3.1. Record OGM
The host will prompt the user to lift the handset to begin OGM recording. The procedure restores the TAM Hands-
Free settings before completion.
Table 128. TAM Hands-Free Review OGM
Host to Modem Commands
/ Data
Modem to Host Result
Codes/Data
Local Modem Actions
AT+VGT=128 OK
Set the RS232-to-Si3000 transmit gain (UB8) for TAM
Hands-Free.
AT+VSM=4 OK
Select G.711U
-law PCM, 8-bit, 64 kbps format. The
voice driver will need to track the OGM format with the
OGM PCM file.
AT+VTX CONNECT Trigger transmit operation.
<DLE><u>
TX Underrun. Appears at the start of +VTX before trans-
mit data are seen.
[Voice Stream]
Transmit OGM voice stream. During voice stream cap-
ture, the user can adjust the UB8 value via the
<DLE><u> and <DLE><d> commands. The host voice
driver will need track the number of adjustments and
update the +VGT value for future use.
<DLE><ETX> OK
Terminate the transmit operation. The modem will
respond with OK to denote the return to command
mode.