Connecting to an IP WAN

Connecting to an IP WAN
The previous chapters have focused on Voice over IP (VoIP) within the IP network at a
single site. The gateway in such a setup would interconnect public switched telephone
network (PSTN), PBX, and other plain old telephone service (POTS) endpoints with voiceenabled
IP endpoints, such as IP phones. VoIP over the WAN has several applications, such
as connecting multiple sites, allowing service providers to terminate long-distance and
local voice calls, providing voice services to telecommuters, and so on.
In this chapter you will learn
ã Applications for connecting to an IP WAN
ã Design considerations when using VoIP over an IP WAN
ã Quality of Service issues and solutions
ã Configuring Quality of Service to fit a provider’s MPLS standards
ã Providing fax and modem services within a VoIP network
ã Ways to secure your VoIP traffic
Applications for Connecting to an IP WAN
Connecting voice gateways over an IP WAN allows you to send voice and video to other
locations as IP packets. For businesses that have geographically distributed offices, using
IP telephony to call between offices can be more cost effective than making long-distance
calls. IP telephony is increasingly becoming a need for businesses that spread their offices
globally. It lets you leverage your investment in WAN bandwidth between offices. The
WAN connection can be a direct circuit between sites, such as a T1; a virtual circuit,
including Frame Relay; ATM permanent virtual circuit (PVC); or a shared connection, as
with a Synchronous Optical Network (SONET) ring. Communication between the voice
gateways could rely on your service provider, such as with Multiprotocol Label Switching
(MPLS), or on the Internet, as when using a virtual private network (VPN) between sites.
Satellite links are also an option, provided their speed and reliability are acceptable.