enable/disable the handover while the MS is using a SDCCH.
For example, it means the MS is on SDCCH in a cell (for any reason, call setup, LU, SMS,…) and a better neighbor cell is measured. A HO will be performed from SDCCH(cell 1) to SDCCH(cell 2).
Other possibilities : low level ul or dl, bad quality ul or dl, etc. (all standard HO causes are verified)