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CUCM ARQs for calls incomming from the GK controlled trunk

What bandwidth request will the CUCM send in ARQ when getting an incomming call?

There has beed some confusion of how the terminating CUCM will allocated bandwidth in the initial ARQ request to gatekeeper.

Let's say we have the following topology, and in our scenario Phone A calls Phone B. since this is the call over the WAN we'd expect it to use 729 codec so in ARQs we'd want to request 16kbs.

Topology

====

PhoneA----CUCM_1----h323 GK----CUCM_2----PhoneB

Let's focus on the region settings of the CUCM_2

====
run sql sqlect * from region

1b1b9eb1-7803-11d3-bdf0-00108302ead1 Default                f 2
0602128d-8215-c359-9e2f-8147abaf349f   Reg-A                 f 2
eb6e3db1-107c-4370-419c-6eb9f653afdf   Reg-B                 f 2
6ef2ae31-a210-aeb6-183a-0e4d10493f2b  Reg-C-G711-only f 2


run sql select * from regionmatrix
pkid fkregion_a fkregion_b tkbandwidth videobandwidth tklossynetwork
==================================== ==================================== ==================================== =========== ============== ==============
afc538cf-9837-11d3-bdf6-00108302ead1 1b1b9eb1-7803-11d3-bdf0-00108302ead1 1b1b9eb1-7803-11d3-bdf0-00108302ead1 64 384 0
290d323a-b311-ea2a-013b-d75fae5c8fb4 eb6e3db1-107c-4370-419c-6eb9f653afdf 0602128d-8215-c359-9e2f-8147abaf349f 10 384 0
6928ccd1-425a-6fe3-14d9-318384958612 6ef2ae31-a210-aeb6-183a-0e4d10493f2b eb6e3db1-107c-4370-419c-6eb9f653afdf 64 384 0
04b5cac1-a58b-b828-d5fc-a41eaf64f23a 6ef2ae31-a210-aeb6-183a-0e4d10493f2b 0602128d-8215-c359-9e2f-8147abaf349f 64 384 0
56653499-1100-b632-ac90-efad784bead2 0602128d-8215-c359-9e2f-8147abaf349f 0602128d-8215-c359-9e2f-8147abaf349f 10 384 0

0240be70-6e52-b452-c144-0e60e2f4fe61 eb6e3db1-107c-4370-419c-6eb9f653afdf eb6e3db1-107c-4370-419c-6eb9f653afdf 10 384 0

We assume that the Phone B is located in region:

eb6e3db1-107c-4370-419c-6eb9f653afdf   Reg-B 

And the GK controlled Trunk is located in

0602128d-8215-c359-9e2f-8147abaf349f  Reg-A             

So the relation between thos two is to use G729 codec.

Let's say the verion of the CUCM is hitting the following defect:

https://tools.cisco.com/bugsearch/bug/CSCsl74701

So to be on the safe site we additionally configure the following under CUCM Service Paramaters>Cisco CallManager:

Default Intraregion Max Audio Bit Rate  8kbs

Default Interregion Max Audio Bit Rate  8kbs

In our scenarion the terminating CUCM will still send the ARQ requesting 128kbs.

But why is that, if the region relatonship between all the enpoints in the terminating CUCM is G729?


The reason is that when terminating CUCM will receive the SETUP message from the CUCM_1 it will check the region relationship between region on the GK trunk, in our case:

0602128d-8215-c359-9e2f-8147abaf349f  Reg-A 

and any othe regions.

04b5cac1-a58b-b828-d5fc-a41eaf64f23a 6ef2ae31-a210-aeb6-183a-0e4d10493f2b 0602128d-8215-c359-9e2f-8147abaf349f 64

So in the case above there is one relationship that has G711 configured. So even no devices from Reg-C-G711-only participate in the call the CUCM_2 will still send ARQ requesting 128kbs. The reason behind this behaviour is that at the time of getting the SETUP message from the other CUCM cluster, we don;t know in which region the call is going to end up.

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