Hey when the call manager is unreachable phones go srst local get there ntp/clock locally I presume so you need to adjust your clock on the router , routers are not very good NTP devices there algorithm would not be as good as the call manager , check your show clock detail to see if the time is NTP or just manually set on router and if its correct and then tweak it using clock set .........
so when you change it does it change the time on the router but not on the phones , how long have you left the phones to sync for ? have your tried restarting one completely to see if it syncs quicker or try an extended ping from router to the phone.
