Welcome to the board!
First let me ask you an initial question:
There were many systems that carried the "Impact" name. What system is this (what's hanging on the wall)?
If you adjust the number of rings in the phone system programming, it will affect the phones during the day AND night. If you use auto attendant during the day, this would likely not work for you, as you would want the opportunity to catch the call that was transferred to you. If you use the Transfer button during the day to get calls from one extension to another, making this change may also present a problem there too, depending on the system you have.
There is a way to do what you want by leveraging the voicemail system, but it is specifically dependent on a time schedule. Relying on a time schedule can present issues on holidays, where unless the holiday is defined, the call will function the same as it would during business hours, assuming the holiday falls on a day when you're normally open. At any rate, setting up this method is more than can be explained in the open forum. Do you have a Comdial tech you normally use to work on your system?
Justin