AASTRA SIP-DECT (Release 1.8)-Installation- and Administration Guide EN - Manual (Page 16)

Installation, Administration and Maintenance
Aastra depl-0900/0.4 Page: 16 (104)
An IP DECT installation is more reliable if a RFP can receive the signal from
more than only one RFP, because the other signals are also used for
synchronization.
The sync-over-air solution is very reliable, because all existing redundant
paths are used for synchronization. Thus, hardware tolerances have only
very little influence. No RFP has a key position.
Only unfavourable setups without redundant synchronization paths can
cause problems.
Sometimes RFPs’ do not need to be synchronized, e.g. if they are in different
buildings. These RFPs’ can be put into different clusters. RFPs’ in different
clusters will not be synchronized with each other. Different clusters start-up at
the same time independently.
2.6 RFP channel capacity
The RFP has 12 available air time slots:
• 8 slots can have associated DSP resources for media streams.
• The remaining 4 slots are used for e.g. control signalling between RFPs’
and PPs’, and hand-in purposes.
If all 8 media stream channels are used the RFP announces a “busy bit”. In
that case the PPs’ determine whether another RFP has an appropriate signal
strength. If so, the PP will handover to that RFP. Once the handover has
been completed, the RFP will then lower its “busy bit”.
Whenever the busy state is announced a log entry is made to the system
logs. If the announcement of busy raises in a specific area, a further RFP
should be installed to double the number of media streams available for calls.