73m2901ce Maxim Integrated Products, Inc., 73m2901ce Datasheet - Page 20

• Manufacturer Part Number: 73m2901ce
• Description: V.22bis Single Chip Modem
• Manufacturer: Maxim Integrated Products, Inc.

73M2901CE Data Sheet
DS_2901CE_031
6.4.6.6 Calling Tone
Calling tone is enabled by setting S28 bit 7 to one. S15 sets the calling tone off time in 100 ms
increments and S16 sets the calling tone on time in 10 ms increments.
6.4.6.7 Call Progress and Data Carrier Transmit Levels
The levels for the carrier and call progress tones (calling tone, answer tone) can be adjusted using the
lower nibble of S13. This can be used to compensate for transmit path losses and to adjust for the
highest transmit levels allowable with a particular hardware configuration and country limitation. The call
progress and data levels can only be changed in 2 dB increments, therefore S13 bit 3 is ignored.
6.4.6.8 Caller ID – Type I and Type II
The 73M2901CE supports worldwide Caller ID (CID) standards. Most of the CID controls are in register
S95, but some are also found in other registers. Looking for the Japanese CID and Type II snoop mode
Marking preamble are controlled by S72 bit 5. S72 bit4 controls Japanese on-hook CID mode. CID
wetting pulse control is controlled by S72 bit 3. Type II CID is enabled with S110 bit 3. When a Type II
CID message is detected, the modem will go back on hook after the message is retrieved.
Register S95 controls all other aspects of the CID mode, such as FSK or DTMF CID, alerting tone
detection, the number of line reversals or rings before CID is expected, and enabling CID. There is also a
continuous CID mode and a DTMF receive mode without a preceding “CID:” so DTMF digits can be
detected. When S95 is set to 99 Hex (ATS95=$99) both US Type I and Type II snoop mode are enabled.
6.4.6.9 ITU Answer Tone Phase Reversals
The 73M2901CE supports ITU answer tone 180º phase reversals during the handshake. Setting S92 bit
6 enables phase reversals and is set to zero by default (no phase reversals).
6.4.6.10 1200 BPS Fast Connect Mode
The 73M2901CE supports the fast connect handshake used in POS terminal applications. Both Bell
212A and V.22 fast connect are supported for the calling side. It does not support the answering fast
connect as exactly defined, but the Ln commands can be used to shorten the handshake time. To use
the calling fast connect handshake, Set register S89 bit 5 (ATS89+64) and set register S30 to Bell 212A
only (ATS30=16). This applies to both Bell 212A and V.22 since the originating side handshake is the
same for both modes. Setting S30 to any other value will override the originate fast connect mode. The
originating fast connect mode will send flags instead of marks if the modem is set for synchronous mode
(Y1 or Y4).
For the answering side, the L1 command will bypass the billing delay and answer tone to significantly
speed up the handshake. This will work with the originating Bell 212A or V.22 fast connect or normal
connect, as well as the standard V.22 bis connection. Of course the fastest connections will be with Bell
212A and V.22 operating in the fast connect mode. L2 will still use the 2-second billing delay, but the
2-second answer tone will not be sent. L3 will use the normal billing delay, and send a short 400 ms
answer tone. L1 will give the fastest handshake with the 1200 bps originate fast connect mode enabled.
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Rev. 3.4