Figure 8-20: Call Flow For Two-Stage Dialing - AudioCodes Mediant 800 MSBG User Manual

Answer Supervision: The Answer Supervision feature enables the FXO device to
determine when a call is connected, by using one of the following methods:
•
Polarity Reversal: device sends a 200 OK in response to an INVITE only when it
detects a polarity reversal.
•
Voice Detection: device sends a 200 OK in response to an INVITE only when it
detects the start of speech (or ringback tone) from the Tel side. (Note that the
IPM detectors must be enabled).
8.3.5.2.1.2 Two-Stage Dialing
Two-stage dialing is when the IP caller is required to dial twice. The caller initially dials to
the FXO device and only after receiving a dial tone from the PBX (via the FXO device),
dials the destination telephone number.
Two-stage dialing implements the Dialing Time feature. Dialing Time allows you to define
the time that each digit can be separately dialed. By default, the overall dialing time per
digit is 200 msec. The longer the telephone number, the greater the dialing time.
The relevant parameters for configuring Dialing Time include the following:
DTMFDigitLength (100 msec): time for generating DTMF tones to the PSTN (PBX)
side
DTMFInterDigitInterval (100 msec): time between generated DTMF digits to PSTN
(PBX) side
SIP User's Manual

Figure 8-20: Call Flow for Two-Stage Dialing

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Mediant 800 MSBG
Document #: LTRT-12804