From the Club 100 support files (www.club100.org)...

CASSETTE and MODEM SIGNALS

Casette
1 Remote 1
2 Ground
3 Remote 2
4 RxC Receive data for CMT
5 TxC Receive data for CMT
6 Ground
7 Not Connected
8 Not Connected

Modem Interface
1 TL conventional telephone unit
2 Ground
3 RxMD Direct connect to tel (Ring)
4 RxMC Acoustic coupler (MIC)
5 TxMC Acoustic coupler (Speaker)
6 Vdd
7 TxMD Direct connect to tel (TIP)
8 RP Ring Pulse (sic)

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