PSTN Connection Types are also known as Modem Connection Types.
Modem Connection Types are used to group PSTN and SMS outstations and channels that use like communications.
Use Modem Connection Types to specify any particular communication requirements for the outstations on your system. For example, to match outstations and channels due to particular hardware requirements or limitations, or for other logical reasons.
By default, any outstations and channels that communicate with the server via PSTN or SMS are placed into one group, which uses the Standard Modem connection type. However, in order to communicate successfully, the server needs to be notified if any differences in PSTN or SMS communications exist for any channels or outstations. For example, if the type of dial-up modem differs from one outstation to another. This is particularly important when an outstation dials in to the server.
If the channels and outstations on your system use different types of PSTN or SMS connection—for instance, different types of dial-up modem—add representations for the different connection types to the ClearSCADA Server Configuration Tool (see Adding Further Types of PSTN Connection).
Most of the DNP3 outstations on a particular ClearSCADA system communicate using a standard modem connection.
However, two of the DNP3 outstations communicate using a connection that requires a special dial-up modem. An additional modem connection type is configured to indicate this requirement. Additional channels are configured on which this connection type is specified. The database is configured to reflect the fact that these particular outstations use these channels to communicate with the server.