I would like to add some more info.
There are 2 Terms known as “Paging coordination” or “IMSI Co-ordination”.
The MSC and SGSN provides BSS with information regarding which IMSI belongs to which connection and by coordinating the IMSI information from the CS and PS domains the BSS can make the paging handling more efficient. At both PS and CS paging the IMSI is used to coordinate that the paging message is always sent on a channel that is monitored by the DTM MS. That is, on PACCH when CS paging is performed in packet transfer mode, on FACCH when PS paging is performed in dedicated mode, and else on PCH/PPCH.
DTM and the IMSI coordination also has the benefit that non-DTM capable MSs can be reached by a CS page when in packet transfer mode regardless of network operation mode (regardless of whether the Gs interface is used or not). This functionality is available also when DTM is turned OFF in a cell, but the feature must be available. One exception is when the MS is involved in a pure UL transfer, Then DTM needs to be enabled in the cell to ensure that CS page is sent on the PACCH.
By sync,did you mean these co-ordinations or else?