If that works for your customers, that’s great. Any business that presents a busy signal to me in the 21st century would probably not get a call back.
You would have been better off to have continued the first thread you started (edit: oops, I see now that thread’s been closed), since nobody here will have a clue what you’re talking about. On your original setup, you had a custom extension with a dial string to a ring group. Instead of that, try putting individual extension dial strings separated by an & character like this:
SIP/5005&SIP/5004&SIP/5003
where the digits are your extension numbers. If you are using pjsip for your extensions, the dial string would look like:
PJSIP/5005&PJSIP/5004&PJSIP/5003
And you can mix and match if you have a mix of each. Then you need to ensure you have the proper skip busy option set for your queue. Add the custom extension as a static agent and retest.