There are many VIP sites. A few of them facing transmission problems. To avoid this problems effects to BTSs we create a site redundancy method which the transmission path problematic sites can work via two BSCs with different priority. At that point, if the prio-1 transmission path down, prio-2 directly works directly via another BSC and the site just reset. After reset, site will be up again. So it increase the user experience so high.