What we used for testing was TEMS Investigation 4.0 with two phones, a T62u and a R520m. I should review the logs file but I think that the MS could decode the SCH from the serving site but not the SCH from the neighbors.
Did you check the frame offset and quarter bit offset? Do you know what’s the acceptable drift?
What’s the synchronization source of your network, do the Base Stations get their own clock from a GPS source or from the T1’s?
In our case we use the T1 as synchronization source, and currently we have a T1 expert investigating this issue.
Are you working with Ericsson BTS or Nokia?