Silicon Laboratories SI2494/39 manual SMS Support, Japan Caller ID, Protocol, SMS Commands

AN93

Table 95. Japan Caller ID

Command Function

AT+VCID = 1 Enables Caller ID.

AT+VCDT = 3 Selects Japan CID mode.

6.3.5. DTMF Caller ID

DTMF Caller ID is supported in the Si2493/57/34/15/04 Revision D or above and Si2494/39 Revision A or above. DTMF Caller ID detection is needed to provide complete CID support for Brazil, China and other countries. The ISOmodem detects the preamble and start code (0x41, or ASCII 'A'), then echoes CIDM to the host. The ISOmodem assembles the rest of the characters in the message and sends them to the host. It detects the stop code (0x44, or ASCII 'D') and proceeds with the rest of the call processing.

For ISOmodems that support voice mode, detection of DTMF CID is done automatically in +FCLASS = 8 mode after being enabled by a “+VLS = 14” command. The user can also enable FSK CID with the AT+VCID and AT+VCDT commands. This gives simultaneous support of DTMF and FSK modes.This is useful in countries like Brazil, China and Taiwan, where the use of DTMF or FSK varies from region to region.

6.4. SMS Support

Short Message Service (SMS) allows text messages to be sent and received from one telephone to another via an SMS service center. The ISOmodem provides a flexible interface that can handle multiple SMS standards. This flexibility is possible because most of the differences between standards is handled by the host in the data stream itself. The ISOmodem performs the necessary data modulation and provides two options for message packet structure (Protocol 1 and Protocol 2, as defined in ETSI ES 201 912). The rest of the data link layer and transfer layer are defined by the host system. The ISOmodem uses a V.23 half-duplex modulation to transmit and receive the data over the PSTN. Protocol 2 differs from Protocol 1 in that a packet is preceded by a 300-bit long channel- seizure preamble. ETSI ES 201 912 describes the other differences between Protocols 1 and 2, but the host processor handles these when structuring the data within the packet.

Table 96. Protocol 1

80 bits of mark (constant ones)

Message

Table 97. Protocol 2

Channel seizure (300-bit stream of alternating ones and zeroes)

80-bit stream

of ones

Message

Four commands control the behavior of the SMS feature, as described in Table 98 below:

Table 98. SMS Commands

Command	SMS Feature Behavior
AT+FCLASS = 256	Prepares the modem for
	handling SMS calls.
ATDT;	Goes off-hook and returns to
	command mode. If a phone
	number is provided, it is dialed
	prior to returning to command
	mode.

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