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AN93
Rev. 1.4
161
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.
Four commands control the behavior of the SMS feature, as described in Table 112 below:
Table 110. Protocol 1
80 bits of mark (constant ones)
Message
Table 111. Protocol 2
Channel seizure (300-bit
stream of alternating ones
and zeroes)
80-bit stream
of ones
Message
Table 112. 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.
AT+FRM = 200
Returns to data mode prepared
to receive an SMS message.
AT+FTM = 201
Returns to data mode prepared
to transmit an SMS Protocol 1
message.
AT+FTM = 202
Returns to data mode prepared
to transmit an SMS Protocol 2
message.
Содержание Si2404
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Страница 200: ...AN93 200 Rev 1 4 Figure 31 TAM Handset and Speakerphone Voice Paths ...
Страница 201: ...AN93 Rev 1 4 201 Figure 32 Si3000 Codec Gain and Signal Selection Options ...
Страница 290: ...AN93 290 Rev 1 4 Figure 57 256 Band Spectral Display Figure 58 2048 Band Spectral Display ...
Страница 305: ...AN93 Rev 1 4 305 Figure 76 Parallel or SPI Port Interrupt Service Flowchart ...