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Advanced Options for Voice Services
VoIP-to-PSTN and PSTN-to-VoIP Calling
Cisco SPA232D Administration Guide 218
C
• If the PIN does not match one of the configured PSTN PIN values, then the
ATA device plays the reorder tone and then takes the LINE port on-hook.
NOTE You can configure these settings in the PSTN Timer Values (sec) section of the
PSTN (LINE Port) page. You can configure caller authentication in the Gateway
Setup sections of the PSTN (LINE Port) page.
Terminating Gateway Calls
There are two call legs in a PSTN gateway call: the PSTN call leg and the VoIP call
leg. A gateway call is terminated when either call leg is ended. When the call
terminates, the LINE port goes on-hook so the PSTN line is available for use. The
ATA detects that the PSTN call leg is ended when one of the following conditions
occurs during a call:
• The PSTN Line voltage drops to a very low value (this occurs if the line is
disconnected from the PSTN service or if the PSTN switch provides a CPC
signal).
• A polarity reversal or disconnect tone is detected at the LINE port.
• There is no voice activity for a configurable period of time in either direction
at the LINE port.
When any of the above conditions occur, the ATA takes the LINE port on hook and
sends a BYE request to end the VoIP call leg. On the other hand, when the ATA
device receives a SIP BYE from the VoIP during a call, it takes the LINE port on
hook to end the PSTN call leg.
In addition, the ATA device can also send a refresh signal periodically to the VoIP
call leg to determine whether the call leg is still up. If a refresh operation fails, the
ATA device ends both call legs.
You can configure these settings in the PSTN Disconnect Detection section of the
PSTN (LINE Port) page.
VoIP Outbound Call Routing
Calls made from Line 1 are routed through the configured Line 1 service provider,
by default. You can override this behavior by IP dialing, through which the calls can
be routed to any IP address that the user enters. The ATA allows flexible call
routing with four sets of gateway parameters and configurable dial plans. You can
configure this feature in the Gateway Accounts section of the Line1 Settings
(PHONE Port) page.