Types of Voice-Capable Gateways
A clear definition of a voice-capable gateway is a router that provides not only data
services, but runs the proper Cisco IOS firmware that provides voice services.
These services are, in their basic form, the following topics:
Controlling and utilizing Digital Signal Processors (DSP) for processing
analog calls
Providing call processing to a CallManager
Providing routing for VLANs between voice and data subnets
A voice-capable gateway must have sufficient CPU processing power and
system memory to handle these functions, as well as any other AVVID services
that may arise.This is where the majority of problems occur in new VoIP designs
because the wrong gateway is selected. In some solutions, sites will try to use the
same voice-capable gateway for both voice and data services.This means that the
same router provides the telco connection, Internet access point, and VLAN
routing in the same gateway.
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The best solution in this environment is to use a Cisco 1600 Series router for
the Internet connection, and then deploy the 1750 router with the voice-capable
IOS to handle the VoIP solution.This keeps the system routing clean and distinctly
separated from data services. If the site cannot afford to have two gateways in this
type of arrangement, the 2600 Series can perform both data and voice services provided
that it has sufficient memory and that the proper voice hardware is installed.