ZyXEL Communications 802.11g Wireless ADSL2+ 4-port VoIP IAD P-2602HWNLI - Manual (Page 47)

P-2602HWNLI User’s Guide
Chapter 1 Getting To Know the ZyXEL Device 47
The following figure shows a basic example of how you would make a VoIP call through an
ITSP. You use your analog phone (A in the figure) and your device (B) changes the call into
VoIP. Your device then sends your call to the Internet and the ITSP’s SIP server. The VoIP call
server forwards calls to PSTN phones (E) through a trunking gateway (D) to the PSTN
network. The VoIP call server forwards calls to IP phones (F) through the Internet.
Figure 2 Internet Telephony Service Provider Application
1.3.3 Make Peer-to-peer Calls
You can call directly to someone’s IP address without using a SIP proxy server. Peer-to-peer
calls are also called “Point to Point” or “IP-to-IP” calls. You must know the peer’s IP address
in order to do this.
The following figure shows a basic example of how you would make a peer-to-peer VoIP call.
You use your analog phone (A in the figure) and your device (B) changes the call into VoIP.
and sends the call through the Internet to the peer VoIP device (C).
Figure 3 Peer-to-peer Calling
1.3.4 Firewall for Secure Broadband Internet Access
Your device provides protection from attacks by Internet hackers. By default, the firewall
blocks all incoming traffic from the WAN. The firewall supports TCP/UDP inspection and
DoS (Denial of Services) detection and prevention, as well as real time alerts, reports and logs.