Hi @KRosenthal! I'll leave the floor open for others to weigh in, but as of right now, the best solution I can think of is to either edit timesheets manually or grant employees the ability to adjust their timesheets, which I understand can be risky.
Another useful feature is Timesheet Rounding, which can round up a timesheet to say--the nearest 15 minutes, but this would also apply to regular time as well, not just call-ins.
Let me know if you'd like any more information on the above options. :) Looking forward to hearing what others suggest as well!