Grandstream UCMs Peering with Least Cost Routing

Least Cost Routing Grandstream UCM


I have two UCM62XXs at two locations with different extension number ranges:
Location A: UCM6204 (extension range 1000) 
Location B: UCM6204 (extension range 2000).

There is a VoIP Trunk connected in UCM A. Is it possible to make outbound calls from UCM B through UCM A’s VoIP Trunk and vice versa?


Inbound call

Figure 1: This diagram illustrates inbound call flows between UCM A and UCM B

The Service Provider has given the trunk main number as 66925500 and a DID number as 66925501. You can assign an extension with the DDI number (for eg. ext. 1501) in UCM A. After creating a Peer Trunk between UCM A and UCM B, you need to configure the following routes for inbound calls going between these UCMs:

a. UCM A’s Inbound Route (VoIP Trunk)
– Pattern: _66925501 
– Default Destination: External Number/25501 

b. UCM A’s Outbound Route
– Pattern: _25501 
– Trunk: PeerTrunk

c. UCM B’s Inbound Route (Peer Trunk)
– Pattern: _25501 
– Default Destination: Extension/501

Outbound Call

Figure 2: Figure 1: This diagram illustrates outbound call flows between UCM A and UCM B

d. UCM B’s Outbound Route

– Pattern = _9x. 
– Strip: 1 
– Trunk = PeerTrunk

e. UCM A’s Inbound Route (Peer Trunk)

– Pattern = _x. 
– Default Destination: By DID 
– Strip: 0 
– Allow DID Extension: Extension 
– Dial trunk: check

f. UCM A’s Outbound Route

– Pattern = _x. 
– Trunk = VoIP Trunk

Test scenario
When the user wants to calls out to 3123 4567, please dial 93123 4567 on the phone. Digit ‘9’ will be stripped off.

Read here if your setup involves a GSM gateway and multiple UCMs

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