User guide

August 2001 115
Handling Incoming and Outgoing Calls
Answering Calls
Answer calls detected by RHT_WAIT_LINE_ON using
RHT_OFF_HOOK or RHT_SEIZE_LINE. These functions are
interchangeable, so all discussion of RHT_OFF_HOOK also
applies to RHT_SEIZE_LINE.
When RHT_OFF_HOOK answers a call, it automatically
transmits the appropriate answer supervision signal towards
the switch directly connected to your system. The switch relays
this information back to the preceding switching equipment and
so on until the information reaches the originating equipment.
This serves as a signal to the originating office to start billing
the caller.
After transmitting the off hook or answer supervision bit
pattern, RHT_OFF_HOOK waits for a duration specified by
RDG_LOCAL_ANSWER_GUARD_TIME before returning, as
shown in Table 23.
Table 23. RHT_OFF_HOOK Sequence
The guard time is important in case your application needs to
hang up immediately after answering a call. Without a guard
time, the off hook pattern would be on the line for a very short
period of time. The CO could ignore that signal, or consider the
transmission to be an error. Although this situation is correctly
handled in most protocols, it could be a problem in some specific
scenarios.
Action Duration
Transmit answer signal
Wait RDG_LOCAL_ANSWER_GUARD_TIME
Return