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56K Softmodem
Command Reference
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Table 3-62: Valid <direction> Values
The <compression_negotiation> parameter tells the modem whether it should
disconnect if V.42 negotiations fail. The 56K Softmodem AT command set does
not support the disconnect feature when V.42 negotiation fails and the
<compression_negotiation> parameter is always set to 0. The <max_dict> and
<max_string> parameters specify the maximum number of dictionary entries and
maximum string length for the modem to negotiate. Their default values are 4096
and 32, respectively.
Table 3-63: +DS Extended Syntax Commands
+DS44=<direction>,<compression_negotiation>, <capability>,
<max_codewords_tx>,
<max_codewords_rx>,<max_string_tx>,<max_string_rx>,<max_history_tx>,<m
ax_history_rx>— V.44 Data Compression
Use this command to configure the V.44 data compression method used by the
modem. The 56K Softmodem never disconnects if V.44 is not negotiated and
always use the streaming method for data transfers. As a result,
<compression_negotiation> and <capability> are always 0.
+DS44=<direction>,<compression_negotiation>, <capability>,
<max_codewords_tx>,
<max_codewords_rx>,<max_string_tx>,<max_string_rx>,<max_history_tx>,<m
ax_history_rx>
Result codes:
OK if <direction> = 0—3, and <compression_negotiation> = 0, and <capability> =
0, and <max_codewords_tx> = 512, 1024, 2048, and <max_codewords_rx> =
512, 1024, 2048, and <max_history_tx> = 1024, 2048, 4096, 1536, 3072, 6144,
and <max_history_rx> = 1024, 2048, 4096, 1536, 3072, 6144.
ERROR if <direction> does not equal 0—3, or <compression_negotiation> does
not equal 0, or <capability> does not equal 0, or <max_codewords_tx> does not
Value Meaning
0 Modem negotiates no V.42 bis compression.
1 Modem negotiates transmit only V.42 bis compression.
2 Modem negotiates receive only V.42 bis decompression.
3 Modem accepts V.42 bis compression in both or either direction (default).
Command Description
+DS=<direction>,<0>,<max_dict>,<max_string> Configures modem V.42 compression method.
+DS? Displays the current V.42 compression configuration.
+DS=? Displays the supported V.42 compression setting.