Nortel CS 1000 Manual page 21

ATTENTION
If two or more independent SIP DECT systems have overlapping coverage
areas, configure these systems so each has a unique subset or portion of
carriers. When each system has a unique subset of carriers, interference
between the systems is reduced.
Reducing the number of available carriers reduces the maximum number of
simultaneous calls in the DECT system. To achieve your desired call capacity,
you can be required to install extra DAPs. For more information, see step 4 of
Configuring DECT Settings.
The DAPs transmit with a minimum of two channels carrying primary voice
and data, also named bearers. If no voice calls occur over a DAP, the
DAP transmits two dummy bearers. If one or more voice calls occur on the
DAP, one is one a dummy bearer, while the others are voice calls.
Synchronization hierarchy
If two or more DAPs belong to the same system, the DAPs automatically
synchronize using a hierarchical structure. In most cases synchronization
is automatic, but if your system has a complex DAP cell structure, you
must manually configure synchronization.
The DAP controller tracks the synchronization structure and assigns each
DAP a unique Radio Part Number (RPN) after the DAP starts the first time.
One or more DAPs act as a synchronization source to form the root of
the hierarchical structure, as illustrated in
hierarchy" (page
Figure 3
DAP synchronization hierarchy
21).
Nortel Communication Server 1000
SIP DECT Fundamentals
NN43120-123 02.02 30 March 2010
Copyright © 2008-2010 Nortel Networks. All Rights Reserved.
Deployment requirements 21
Figure 3 "DAP synchronization