2.4.2.8 Call Accept, Reject, and Redirect

In environments like ISDN, call offering is separate from alerting. In fact, after a call has been offered to the TAPI DLL, a time window exists during which the TAPI DLL has a number of options.

The TAPI DLL can simply answer the call using TSPI_lineAnswer (described earlier).
The TAPI DLL can reject the offering call using TSPI_lineDrop. The call remains valid but transitions to the idle state.
The TAPI DLL can accept the call using TSPI_lineAccept, which will initiate alerting to both the caller as ringback, and the called party as ring.
The TAPI DLL can redirect the call using TSPI_lineRedirect, which deflects the offering call elsewhere. The call remains valid but transitions to idle.

TSPI_lineAccept

Accepts an offered call and start alerting of both caller (ringback) and called party (ring).

TSPI_lineRedirect

Redirects an offering call to another address.