Specifications

4-3
Linksys ATA Administrator Guide
Document Version 3.1
Chapter 4 Configuring the PSTN Gateway (FXO)
How VoIP-To-PSTN Calls Work
Note If Authentication is disabled, a default dial plan is used for all unknown VoIP users.
Two-Stage Dialing
In two-stage dialing, the SPA3102 takes the FXO port off-hook but does not automatically dial any digits
after accepting the call. To invoke two-stage dialing, the VoIP caller should INVITE the PSTN Line
without the user-id in the Request-URI or with a user-id that matches exactly the <User ID n> of the
PSTN Line. A different user-id in the Request-URI is treated as a request for one-stage dialing if
one-stage dialing is enabled, or dropped by the SPA3102 (as if no user-id is given) if one-stage dialing
is disabled.
Note If Authentication is disabled, a default dial plan is assigned to all VoIP callers.
HTTP Digest Authentication can be also used for two-stage dialing, as in one-stage dialing. If using
HTTP Digest Authentication or Authentication is disabled, the VoIP caller should hear the PSTN dial
tone right after the call is answered (by a SIP 200 response).
If PIN Authentication is enabled, the VoIP caller is prompted to enter a PIN number after the SPA3102
answers the call. The PIN number must end with a # key. The inter-PIN-digit timeout is 10 seconds (not
configurable). Up to eight VoIP caller PIN numbers can be configured on the SPA3102. A dial plan can
be selected for each PIN number. If the caller enters a wrong PIN or the SPA3102 times out waiting for
more PIN digits, the SPA3102 tears down the call immediately with a BYE request.
Note When the source address of the INVITE is 127.0.0.1, authentication is automatically disabled because
this is a call by the local user. This applies to both one-stage and two-stage dialing.
Table 1-28 lists the parameters used in two-stage dialing.
Table 1-27 VoIP User Account Information
Parameter Group Description Values
User ID
1/2/3/4/5/6/7/
8
PSTN
Line
The username value. 31-character string
Password
1/2/3/4/5/6/7/
8
PSTN
Line
The password value. 31-character string
User
1/2/3/4/5/6/7/
8 DP
PSTN
Line
Specifies the dial plan to be used for this VoIP
user. If 0, dial plan processing is disabled; the
given target number is dialed to the PSTN as is.
Choice of 0-8