Silicon Laboratories SI2494/39 manual TAM Hands-Free Review OGM, Record Local ICM, Review ICM

AN93

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.

	Table 128. TAM Hands-Free Review OGM
Host to Modem Commands	Modem to Host Result	Local Modem Actions
/ Data	Codes/Data
AT+VGT=128	OK	Set the RS232-to-Si3000 transmit gain (UB8) for TAM
		Hands-Free.
AT+VSM=4	OK	Select G.711U μ-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.
		Transmit OGM voice stream. During voice stream cap-
[Voice Stream]		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.

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.

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