9:00 pm PST might be unsuitable for CST time zone
When planning a call between Pacific Standard Time and Central Standard Time, you need to consider time difference between these time zones. PST is 2 hours behind of CST.
It is 9:00 pm in PST. This does not fall within the span of usual working time between 11:00 am and 6:00 pm in CST, but it still might be suitable to arrange a meeting, since it would be 11:00 pm in CST, which is between 7:00 am and 11:00 pm CST time.