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Call Routing

We have 3 different office locations and an extension 5678 which exists locally at each location. 
-5678 in HQ_Partition
-5678 in BR1_Partition
-5678 in BR2_Partition

CSS are defined for each site to direct the calls and is working perfectly fine. When someone at BR1 dial 5678, call routes to the phone at BR1.

Recently got a DID line xxxx 5678 from our TSP, because we wanted this number to be reachable for external callers. 
Now, we would like to point that DID to HQ_Partition only, meaning someone externally dials XXXX 5678 , the call gets routed to phone at HQ.

Is this possible? If so, how? Please guide.


Just add the HQ_Partition to the CSS, that is configured on the SIP trunk or H.323 GW (whatever you are using to connect to the TSP via the router)

And then use a Translation Pattern to strip it down to 4-digits (also this Translation pattern should contain a CSS, which only has access to the HQ_Partition).


If you have managed to already split up the internal dialplan, the concept remains the same, if calling from external.



If I understood it correctly, all internal location partitions might be a member of the existing SIP trunk/GW inbound CSS to allow the incoming DDI  calls. (Assuming centralised PSTN/SIP connection). 

I will try the following way, 

  1. Create a partition 5678_HQ_Partition and assigned it to DN or TP depending on the dial plan
  2. Assign the 5678_HQ_Partition to all HQ CSS's  [if step 1 is DN]and the Inbound CSS of the Trunk/GW.

Assuming, you are only sending the last 4 digits from the GW to the call manager.  you should get an idea now by reading @b.winter and this post. IF you are still not clear, kindly share the following details. 

  1. Significant Digits from Call Routing Information - Inbound Calls (Gateway / Trunk configuration


Nithin Eluvathingal
VIP Mentor

From DID xxxx 5678  strip XXXX, this can be done from the gateway using voice transaltion rules or from CUCM gateway/trunk using

Here is my gateway configurations where i allow only the last 4 digit from my DID.


Screenshot 2022-04-25 131948.png


I have CSS-OMN-Internal on gateway, with this css i can reach the partitions which belongs to CSS-OMN-Internal.


In your case, assign the css has  HQ_Partition so people can reach 5678 from outside.

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