Installation guide

DSP resources and licensing for IP telephony resources 28-5
Chapter 28: Understanding Wave IP Telephony
Wave Global Administrator Guide
The number of DSP resources you have available for IP telephony on your Wave Server
depends upon the hardware installed on your system and the IP Gateway licenses that you
purchase.
How many DSPs do you need?
The more DSPs you allocate to IP telephony in the Resource Management configuration, the
more concurrent IP calls your system can support. To estimate the number of DSPs you require
at each site, remember that each time a transition is made between TDM voice signals and
packets in the voice path, a DSP is required to make the conversion.
Note: Calls between IP phones do not require any DSPs on the Wave Server.
Most IP calls will require two DSPs, one at each end of the IP segment of the call. The DSPs
may be located on the Wave Server, or they may be located on the IP phones, depending on the
calling scenario.
DSP resources required in a site-to-site scenario
The following diagram shows the DSPs required in a direct site-to-site IP call scenario over a
packet-switched network segment. (See “Direct site-to-site IP calls” on page 28-8 for a detailed
explanation of this scenario). In this scenario, the phones are traditional TDM calling devices
(the analog or digital phones).
A DSP on Wave Server A translates the voice signal (from the caller at extension 101) into
packets that can be sent over the IP network. The receiving Wave Server B uses a DSP to
translate the packets back into a voice signal that can be understood by the call recipient at
extension 201, and vice versa. If you want to support four calls of this type at once, each Wave
Server would require four IP telephony DSP resources.
101 201
Wave ISM A
packets packets
voice
signal
Wave ISM B
IP
DSPDSP
TDM
voice
signal
TDM
Release 2.0
September 2010