How to reject calls over the first one?

I wish to reject all incoming calls with a busy tone if at least one trunk is in a call, this because the office is small and if a people is making a call, it is annoying that the other two extensions ring.
I placed call-limit=1 in incoming trunk but there is an hangup without caller receive a busy tone.
I have not modified nothing and it worked in the desired way… I don’t understand at all!
Log says:
chan_sip.c: Call from peer ‘SIP-XXXXX’ rejected due to usage limit of 1
chan_sip.c Failed to place call for device (phonenumber), too many calls
executing [[email protected]:1] Macro (" SIP/SIP-XXXXXX-000008d9",“hangupcall,”) in new stack

I tried also to make a custom context and place a code for busy tone… but I don’t know if this code has been executed…
The context that I created is context=XXXXXX that I placed on Trunk web page

Thanks for your support

this is just a guess so forgive me if it is wrong… if it were me, I would create a group and put the extension that answers the one phone call in it. then in the group skip busy agents to yes, then at the bottom, Destination if no answer create a custom destination? busy tone? again just a guess. you maybe able to do that with just an extension…

check out Call Flow Toggle Control, looks like that will do exactly what you want!

wHERE is that setting?
Call Flow Toggle Control

I checked … Totally Useless for my problem