CUCM with multiple gateways and PRI connections

Answered Question
Feb 14th, 2008
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Hi,



I am looking for a some feedback to see if this is a feasible solution. With CUCM 6.0 I want to set up 2 2811 routers as the gateways, and have 1 PRI terminated in 1 2811 (30 channels) and 1 PRI terminated in the other 2811 gateway (15 channels). Is this kind of setup feasible, ideally Id like CUCM to recognise when the 30 channels on the main 2811 are in use, and then use the additional 15 channels on the secondary 2811 when they are needed.


Im pretty new to voice, so am not fully aware of the capabilities for splitting the PRI's between 2 gateways.


Thanks

Correct Answer by Rob Huffman about 9 years 3 months ago

Hi Jo,


You are most correct my friend, when all the channels on the first PRI are busy then the second PRI will be selected for use :) Look under Call Routing Configuration in this rather large CCM 6.x pdf;


http://www.cisco.com/en/US/docs/voice_ip_comm/cucm/admin/6_1_1/ccmcfg/bccm.pdf


Work with the Telco to make sure what order the calls are coming in on and you can maximize the use of both PRI's. For example, if you Incoming calls are starting on the 30 Channel PRI - Channel 1 you might want to start your Outgoing calls on the 15 Channel PRI - Channel 15. It's pretty flexible. So for our 4 PRI's the flow might be;


2811 # 1 - PRI 1&2


2811 # 2 - PRI 3&4


Incoming calls cycle through 1,2,3 and 4


Outgoing calls cycle through 4,3,2 and 1


Hope this helps!

Rob

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Rob Huffman Thu, 02/14/2008 - 10:09
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Hi Jo,


Yes, this is a "supported" and highly recommended practice. We use 2x2811's and then split our PRI's over these Gateways. DID calls can route over any of these PRI's via Route Group/Route Lists that contain all Gateways. If one of the 2811's or VIC modules fails (B-Channels will Busy-Out) and calls are still routed over the remaining 2811 Gateway.


Hope this makes sense!

Rob


jo-knight Thu, 02/14/2008 - 11:04
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Rob,


Thanks for the reply. I will check out the documentation for Route Groups and Route Lists.


So I take it with this, it will also use the additional 15 channels on the 2nd 2811 when all 30 channels are in use on the primary PRI?


Jo

Correct Answer
Rob Huffman Thu, 02/14/2008 - 11:34
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Hi Jo,


You are most correct my friend, when all the channels on the first PRI are busy then the second PRI will be selected for use :) Look under Call Routing Configuration in this rather large CCM 6.x pdf;


http://www.cisco.com/en/US/docs/voice_ip_comm/cucm/admin/6_1_1/ccmcfg/bccm.pdf


Work with the Telco to make sure what order the calls are coming in on and you can maximize the use of both PRI's. For example, if you Incoming calls are starting on the 30 Channel PRI - Channel 1 you might want to start your Outgoing calls on the 15 Channel PRI - Channel 15. It's pretty flexible. So for our 4 PRI's the flow might be;


2811 # 1 - PRI 1&2


2811 # 2 - PRI 3&4


Incoming calls cycle through 1,2,3 and 4


Outgoing calls cycle through 4,3,2 and 1


Hope this helps!

Rob

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