The concept of max-calls per button and busy trigger is quite easy but has been made complex.
max-calls-per-button is used for maximum calls (incoming and outgoing) which can go through that line.
busy-trigger-per-button is used to busy out incoming calls after the parameter set has been reached. So if an ephone has busy-trigger-per-button set to 2 and the phone has two active calls then the third call will go to voicemail (if set), busy tone or forwarded to another number if call-forward noan is set.
huntstop channel is used on a shared line for incoming calls, rest of the channels are reserved for outgoing calls.
In the following scenario, I have configured following:
– Phone 1 can only take 4 inbound calls
– Phone 2 can only take 2 inbound calls
– Shared line of Phone 1 & Phone 2 can take 5 inbound calls
ephone-dn 1 octo-line
number 3001 no-reg primary
description +56576513001
name “Phone 1”
call-forward busy 3220
call-forward noan 3220 timeout 20
!
!
ephone-dn 2 octo-line
number 3002 no-reg primary
description +56576513002
name “Phone 2”
call-forward busy 3220
call-forward noan 3220 timeout 20
!
ephone-dn 3 octo-line
number 3003 no-reg primary
description +56576513003
huntstop channel 5 << Shared line – only inbound calls
!
!
ephone 1
privacy-buton
mac-address XXXX.XXXX.XXXX
ephone-template 1
max-calls-per-button 5 << inbound & outbound
busy-trigger-per-button 4 << only inbound
button 1:1 2:3
!
ephone 2
privacy-button
mac-address XXXX.XXXX.XXXX
ephone-template 1
max-calls-per-button 5 << inbound & outbound
busy-trigger-per-button 2 << only inbound
button 1:2 2:3
Above, shared line 3003 is shared between ephone 1 and ephone 2. If there are two active calls on ephone 2 then the third incoming call will ring ephone 1 as ephone 2 will reach its busy-trigger. The third, fourth and fifth call come and ring ephone 1 but the sixth call will hit huntstop channel for shared line ephone-dn 3 and will not be handled.
voiceonbits.com 
Again great post Ashar.
Does any body recently appeared in the ccie voice lab exam.I mean in Aug 2010.
Need folks feed back what topic it is covering. Like vpim or features like extension mobility.
I heard cisco removed one of the scenario from the lab.
He replaced this with something else.Does any body know?
Thanks
This is NOT good configuration as those requirements cannot be accomplished with above shown config. Did you test your configuration at all?
make the following test with it and tell me if it works 🙂
all calls are made to 3003
answer first incoming call on ephone 2, leave it on, don’t end it
answer 2nd incoming call on ephone 2, leave it on, don’t end it
now, your busy trigger will play a part and 3rd incoming will not ring on ephone 3.
so make 3rd call in to 3003 and it will ring on ephone 1 only
so far so good
answer it on ephone 1, don’t end it
now make 4th call to 3003 and it will ring ephone 1 only again, answer it and don’t end it
so now, we have curently 4 incoming calls to 3003 out of which 2 are answered on ephone 2 and 2 on ephone 1, right?
so far so good 🙂
but gotcha comes here…
make a 5th call to 3003 (as per requirements above, that call should be allowed and since ephone 1 didn’t reach busy trigger 4 yet, that call should be ringing on ephone 1, right?
WRONG!!!
make a 5th call in and you will get BUSY.
this is b/c busy trigger on shared line is counted against shared line no matter who answers the call. so first 2 calls answered on ephone 2 are also counted agains busy trigger setting of ephone 1 as well hence ephone 1 currently has 4 calls counted as it is using the same shared line hence 5th call will not go through!
so, I would gladly see that this requirements can be met but unfortunatelly I am not so sure that could be achieved as you stated it.
please prove me I am wrong and show me how to achieve that 🙂
This is working fine as I only post stuff after testing.
Try this way:
Call shared line 3003 and receive it at Ph1.
Make a 2nd call to 3003 and receive it at Ph1.
Make a 3rd call and received it at ph1 again.
Make 4th call and receive it at Ph1.
Now you have four active calls on Ph1.
Make a fifth call and receive it at Ph2.
Now five calls are active at shared line 3003.
Make a sixth call and you will hear a busy tone.
Hi Ashar,
I configured it the same way but 5th call always gives me busy.
can u please cross check this?
i tried to test the ways u wrote above.
I couldn’t make this work either, has anyone got any luck with configuring this one?
Thanks
Guys, Please follow the steps as written and it will work. You guys must be making some mistake.
Hi Guys,
The config works, but i think there is a misunderdstanding about it. The shared line supports 4 inbound calls ( only inbound ) since ephone 1 accepts 2, ephone 2 accepts 2 incoming calls, but the above config provide 5 “concurrent” calls through shared line, both incoming and outcoming directions. As per this aspect, you are able to make an outbound call, 5th call through shared line, while 4 incoming calls were received. If you try to make 6th call, then you will get busy tone because of ” hunt stop channel 5 “.
Hi,
I have a question that will kill me.
What about the SIP Phones, voice register dn ? Does not have dual/octo line.
¿?
Thanks for the post and feedback. I never tested it, but I’d tend to agree with djuvecka.
“make a 5th call in and you will get BUSY.
this is b/c busy trigger on shared line is counted against shared line no matter who answers the call. so first 2 calls answered on ephone 2 are also counted agains busy trigger setting of ephone 1 as well hence ephone 1 currently has 4 calls counted as it is using the same shared line hence 5th call will not go through!”
The config seems very similar to what’s in the doc.
http://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cucme/admin/configuration/guide/cmeadm/cmebasic.html#pgfId-1105668
“Shared Octo-Line Directory Number
In the following example, ephone-dn 7 is shared between phone 10 and phone 11. There are two active calls on ephone-dn 7. A third incoming call to ephone-dn 7 rings only phone 11 because its busy-trigger-per-button command is set to 3. Phone 10 allows a total of three calls, but it rejects the third incoming call because its busy-trigger-per-button command is set to 2. A fourth incoming call to ephone-dn 7 on ephone 11 is either rejected with a busy tone or forwarded to another destination if Call Forward Busy is configured. The phone user can still make an outgoing call or transfer or conference a call on ephone-dn 7 on phone 11 because the max-calls-per-button command is set to 4, which allows a total of four calls on ephone-dn 7 on phone 11.
ephone-dn 7 octo-line
number 2001
name Smith, John
huntstop channel 4
!
ephone 10
max-calls-per-button 3
busy-trigger-per-button 2
mac-address 00E1.CB13.0395
type 7960
button 1:7
!
ephone 11
max-calls-per-button 4
busy-trigger-per-button 3
mac-address 0016.9DEF.1A70
type 7960
button 1:7”