128 Configuring a modem for TM 3.0 applications553-3001-230 Standard 10.01 September 2007Procedure 22Changing the factory INIT string1 From the Start menu, select Settings > Control Panel > Phones and Modems >Properties > Advanced2 Type in the appropriate INIT string.End of ProcedureConfiguring high-speed smart modemsAs modem technology progresses, the new generation of high-speed modems providesadditional functionality to achieve the highest possible connection rate. Thesehigh-speed smart modems use various tones during the handshaking period to negotiatethe speed and protocol.SDI portThe modem configured on the SDI port needs extra attention. In most cases, the modemattached to the SDI port is configured to run in dumb mode at the same speed for whichthe system SDI port is configured (at 9600 bps or less). This locks the modem into aspecific mode of operation, preventing it from running in command mode (echo input)or from connecting at a different baud rate than is configured for the system SDI port.Prevent lockupWhen a high-speed smart modem is used on the TM 3.0 PC to dial up the systemmodem, the PC modem always attempts to connect at its highest possible speed. Thesystem’s modem, however, can only connect at the configured speed. Therefore, duringthe modem online handshaking period, the PC modem sends out different tones tonegotiate the speed and protocol, and the switch modem connects at its configured speedand ignores additional attempts.When the switch modem is connected, any additional handshaking tones sent by PCmodem are translated into data (garbage under this condition) and forwarded to thesystem SDI port. These garbage characters can eventually lock up the system port. Thetwo modems can still be connected, but access to the system overlay input is no longerpossible.To avoid this type of problem, the key is to maintain modem compatibility. To avoidpotential problems and increase the connection success rate:• Configure the PC modem to match the switch modem’s settings.
