Symptom:

The ScheduledCall table continues to grow despite purge jobs being run under Administrative Tools > TMS Server Maintenance. The purging of ScheduledCall table can stop working causing unchecked database growth in the tmsng database due to null Guid entries within the database. Note that the purge job itself doesn't necessarily fail when it's scheduled to run, it just fails to delete any rows of data.

Conditions:

Under Administrative Tools > TMS Server Maintenance, if you see your Scheduled Calls table growing versus shrinking after purge jobs have run, customers can check how many rows they have with a null Guid by running the following SQL query against the tmsng database:

select count(*) from ScheduledCall where Guid is null

If the number of rows returned is greater than 30,000 then there is a chance that the purge procedure will fail.