Voip Features - ZyXEL Communications P-2612HNU-F1 User Manual

You can also configure firewall on the ZyXEL Device for secure Internet access.
When the firewall is on, all incoming traffic from the Internet to your network is
blocked unless it is initiated from your network. This means that probes from the
outside to your network are not allowed, but you can safely browse the Internet
and download files.
Use QoS to efficiently manage traffic on your network by giving priority to certain
types of traffic and/or to particular computers. For example, you could make sure
that the ZyXEL Device gives voice over Internet calls high priority, and/or limit
bandwidth devoted to the boss's excessive file downloading.

1.2.2 VoIP Features

You can register up to 2 SIP (Session Initiation Protocol) profiles (4 accounts for
each profile) and use the ZyXEL Device to make and receive VoIP telephone calls:
Figure 3 ZyXEL Device's VoIP Application
The ZyXEL Device sends your call to a VoIP service provider's SIP server which
forwards your calls to either VoIP or PSTN phones.
P-2612HNU(L)-FxF User's Guide
Chapter 1 Introduction
PSTN
23