Figure 5-9 Two Sv9100 Systems Connected Via The Wan - NEC Univerge SV9100 Manual

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Another regular device in customer networks that can hinder VoIP

performance is a firewall. Most corporate LANs connect to the public

Internet through a firewall. A firewall is filtering software built into a router or

a stand alone server unit. It is used to protect a LAN it from unauthorized

access, providing the network with a level of security. Firewalls are used for

many things, but in its simplest form, a firewall can be thought of as a one

way gate. It allows outgoing packets from the local LAN to the Internet but

blocks packets from the Internet routing into the local LAN, unless they are

a response to query.

A firewall must be configured to allow specific traffic from the Internet to

pass through onto the LAN.

Figure 5-9 Two SV9100 Systems Connected via the WAN

SV9100 systems. One on the corporate local LAN and one on a Remote

network connected via the WAN. The remote site cannot call the MAIN site,

therefore it is not working.

Figure 5-9 Two SV9100 Systems Connected via the WAN

Headquarters

Remote Network

The green arrow in

Figure 5-9 Two SV9100 Systems Connected via the

represents the data packets leaving the REMOTE IPLE card destined

for the SV91000 on the Headquarters LAN. The firewall on the

Headquarters network is not configured to recognize the TCP/UDP ports

utilized by the NEC equipment thus blocking them resulting in registration

failure. To solve this issue the ports used by the NEC VoIP equipment have

to be opened in the firewall allowing the NEC traffic to pass through to the

The ports, 57000 and 59000 (TCP) for signaling and the voice ports, are

required to be open at each location.

SV9100 IP K-CCIS