AASTRA SIP-DECT (Release 3.0)- OM System Manual - Installation, Administration and Maintenance EN - Manual (Page 158)

SIP–DECT OM System Manual Release 3.0 9 Configuration und Administration Aspects
Aastra depl-1624/1.0 Page: 158 (241)
As long as an RFP is not in sync, no calls can be established using this RFP.
If an RFP loses the synchronization, the RFP does not accept new calls (“busy bit”). There is
a delay of maximum 3 minutes until the active calls on this RFP are finished. Then it tries to
get synchronized again.
A SIP–DECT installation is more reliable if an 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 unfavorable setups without redundant synchronization paths can cause problems.