Terminating Gateway Calls - Cisco SPA2102-AN - Single Port Router Administration Manual

Configuring the PSTN (FXO) Gateway on the SPA3102
How PSTN-To-VoIP Calls Work
NOTE
Cisco Small Business ATA Administration Guide
For information about configuring the timer values for the above scenarios, see
"FXO (PSTN) Timer Values (sec) section," on page
For information about configuring caller authentication on the SPA3102, see
To-PSTN Gateway Setup section," on 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 FXO port goes on-hook so the PSTN line is available for use. The
ATA device 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 FXO port.
• There is no voice activity for a configurable period of time in either direction
at the FXO port.
When any of the above conditions occur, the ATA device takes the FXO 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 FXO 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.
On the SPA3102, these settings can be configured on the Voice tab > PSTN Line
page. For more information, see
page 216.
On the SPA8800, these settings can be configured on the Voice tab > Phone page.
For more information, see
page 183.
211.
"PSTN Disconnect Detection section," on
"FXS Port Polarity Configuration section," on
214.
6
"VoIP-
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