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Chapter 13 VoIP Trunking
P-2302HWUDL-P1 Series User’s Guide
175
13.9.4 Call Progression
The call is initiated by the manager dialing into the headquarter’s ZyXEL Device via PSTN. In
this scenario a VoIP link is established between headquarters and the branch office and then
the call is forwarded to Sales1 using PSTN.
Table 77 PSTN to PSTN: VoIP Trunking Call Progression
MANAGER HEADQUARTERS BRANCH OFFICE SALES1
The manager dials the PSTN number of the headquarters’
ZyXEL Device. (222-222-2222)
The ZyXEL Device receives the call and sends a ringback
alert tone to indicate to the caller that VoIP trunking is
enabled.
The manager dials the PSTN number of Sales1 (555-555-
1234).
The ZyXEL Device prompts the manager to enter the PIN in
order to allow VoIP trunking.
The manager dials the PIN (12345).
The ZyXEL Device confirms the password and allows for VoIP trunking.
The ZyXEL Device inspects the phone number against call rules. Since the number
starts with the pattern (5555), it uses the account (CityB) associated with this pattern to
connect the call to the remote peer device at the branch office.
The remote peer device inspects the number and requests authentication in order to
forward the call.
The ZyXEL Device at A sends outgoing authentication to the remote peer device.
The remote peer device confirms that the username and password match an account in
its incoming authentication list.
The remote peer device forwards the call to Sales1.
Sales1 picks up and the call commences.