Sets property PassthroughMode true switchs into the Passthrough
mode, Sets property PassthroughMode false switchs out of
the Passthrough mode.
Remarks
When a call is active in Passthrough mode, the service provider gives direct
access to the attached hardware for control by the application. Applications
can use this mode for temporary direct control over asynchronous modems, accessed
through the Passthrough_Write or
Passthrough_Read methods, for the purpose of configuring or using special
features not otherwise supported by the service provider, such as facsimile
(Class 1, 2, and so on). This bearer mode is supported by the Universal Modem
Driver (UNIMODEM) service provider.
[Note:From our experience, we can not get fully control of the modems after
it switch out of Passthrough. This is because the modem does not know what
you have done while in Passthrough, and what callstate any calls may be in.
For instance, you may have dialed a call, and the modem/TAPI won't know about
it. ]
