CUCM SIP Trunk full

[Essam Butt]

Hello,

I have a question regarding SIP Trunks and if they are full. I understand the behaviour is that the call fails, but what other options do we have?

Can we overflow the calls to another SIP Trunk or play a message and then drop the call?

Any ideas?

Thanks,

[Flo.Matalis]

Hi, to which scenario are you referring as full? and is it incoming or outgoing calls?

[Essam Butt]

Hi,

I meant simultaneous calls through the trunk. Let's say our SIP Trunk can only handle 50 concurrent calls, what else can we do with the next call? What are our options here other than just declining the call? Can we play a message to the caller?

It's mostly for incoming.

Thanks,

[Nithin Eluvathingal]

I assume you are referring the  TRUNK between your CUBE and Service Provider. Based on the Router model CUBE can Have more than 50 sessions. if you wana  have more call, subscribe more session with your ISP. 

https://www.cisco.com/c/en/us/products/collateral/unified-communications/unified-border-element/data-sheet-c78-729692.html

CUBE Platform Support

Router platform	Minimum memory requirement	Maximum trunk sessions	Maximum sustainable call setup rate (Calls per second)
Cisco 1100 ISR1	Default	500	5
Cisco 4321 ISR	4 GB	500	4
Cisco 4331 ISR	4 GB	1000	10
Cisco 4351 ISR	4 GB	2000	13
Cisco 4431 ISR	8 GB	3000	15
Cisco 4451-X ISR	8 GB	6000	40
Cisco 4461 ISR	8 GB	10,000	55
C8200L-1N-4T	4GB	1500	9
C8200-1N-4T	8GB	2500	14
C8300-1N1S-6T	8GB	7000	40
C8300-1N1S-4T2X	8GB	8000	45
C8300-2N2S-6T	8GB	7500	42
C8300-2N2S-4T2X	16GB	10,000	55
Cisco CSR 1000V /C8000V 1vCPU2	4 GB	1000	5
Cisco CSR 1000V /C8000V 2vCPU2	4 GB	3000	20
Cisco CSR 1000V /C8000V 4vCPU2	8 GB	6000	30
Cisco ASR 1001-X	16 GB	12,000	50
Cisco ASR 1002-X	16 GB	14,000	55
Cisco ASR 1006-X with RP3 and ESP100/ESP100X	16 GB	16,000	65
Cisco ASR 1004 /ASR 1006 / ASR 1006-X with RP2 and ESP40	16 GB	16,000	70

[Essam Butt]

Hi ,

Thanks for your reply. Yes increasing the CUBE sessions is an option but I was thinking more on the configuration side of CUCM/CUBE. Instead of abruptly ending the call, can we play a message or overflow it to another Trunk?

Just another question, SIP Trunks configured on CUCM to CUBE, do they have any limits? like max number of sessions/channels?

Thanks,

[Nithin Eluvathingal]

Playing a message, AFAIK not possible. Busy  tone is what I have commonly seen.

You can subscribe another trunk and have CUBE HA. refer the Cube configuration/Design Guides. 

https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/voice/cube/configuration/cube-book/voi-cube-high-availability-ISR4K.html

Just another question, SIP Trunks configured on CUCM to CUBE, do they have any limits? like max number of sessions/channels? Have look on similar thread. 

https://community.cisco.com/t5/ip-telephony-and-phones/sip-trunk-capacity/td-p/1517254

[Roger Kallberg]

No there is no specific max session on the trunk between CM and your SBC (Cube). It would although adhere to the set limits that you would have defined in the IOS configuration. Or you could use the call admissions control mechanism that is in CM with locations.

On your question, it would depend on the direction of the call. Outbound you can control the path with configuration in CM to select where to send the call to a secondary destination if it gets denied by the primary destination. For inbound it would be up to your service provider to dictate what happens to the calls if it gets denied by the primary destination.