Call waiting -> Decline -> Busy tone? / alternative voicemail greeting?

[JEBs]

Wish you all a Merry Christmas!

After a couple of test with Asterisk and FreePBX I ended up with FreeSwitch + FusionPBX.
Really cool stuff, but terrible complicated , at least for me .

What I'm currently struggle with, is to get the old ISDN "busy on busy" behavior.
Let me describe please:
On my Yealink extension I've "Call waiting" (call knocking) enabled.
When a 2nd call comes in (while I already have an active one), I've the ability to "decline" it, or let him ring.
In the current behavior, the 2nd caller always get connected to the voicemailbox.
In principle good, but then the caller might think that I'm out of the office (and immediate call me on my mobile ).
What I like to get is the old ISDN "busy on busy" behavior. When I press "decline" to the second caller, that he gets a busy tone.
This also happen when I disable the voicemail, but I do want a voicemail-box in general.

In addition I would love to get the possibility to use an alternative greeting text on my voicemail-box. One normal <I'm away> and another <I'm busy> for those two cases.

Is it possible in general?
If "yes" can someone point me into the right direction?

Regards and peaceful Christmas days!!

 

[DigitalDaz]

I'm pretty sure its not possible to get the busy on busy as I think the phones just send a 486 busy when you reject the call.

 

[JEBs]

Hi DigitalDaz!
Thanks a lot for answering!

Yes, currently it send a 486 busy, but if I remember right, it might be configurable.

However, can you please describe a noob why this matters?
In my simplyfied brain I though, I need to have some kind of additional rules inside the dialing rules which would handle the reject (or non-answer) to go somewhere else instead of the voicemail-box...