![](/images/backgrounds/126832/126832-337187x1.png)
Figure 101 PSTN to PSTN Example - Incoming Authentication
13.9.4 Call ProgressionThe 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 78 PSTN to PSTN: VoIP Trunking Call Progression
MANAGER | HEADQUARTERS | BRANCH OFFICE | SALES1 |
|
|
|
|
The manager dials the PSTN number of the headquarters’ |
|
| |
ZyXEL Device. |
|
| |
|
|
| |
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 |
|
| |
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. |
|
|
|
|
|
|
Chapter 13 VoIP Trunking | 187 |