scenario: if i phonecall you and you missed it...

missed call = 09:00 to 12:00
expected response time =/less than 18:00 (same day)

missed call = 12:01 to 18:00
expected response time =/less than 00:00 (same day)

missed call = 18:01 to 00:00
expected response time =/less than 12:00 (following day)

the above also applies to text messaging.

failed to response within expected timeframe via phonecall or sms?

Don't bother anymore