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Trunk Asterisk - Cucm

Level 1
Level 1


I have a problem with the trunk between CUCM and Asterisk.

I can make a call from CUCM to Asterisk, and there is no problem.

I can't make a call from Asterisk to CUCM.

In Asterisk's log i can see that my call is send to the trunk, with right number.
And i have a error:
Got SIP response 503 "service unavailable"
SIP/trunk-cucm is circuit-busy

I can't find this call in log in CUCM.

My phone in CUCM is in a calling search space, that is used in my trunk configuration.

Thanks all


5 Replies 5

Brandon Pierce
Level 4
Level 4

The CSS of the phone is irrelevant, does the Trunk CSS have the phone's partition listed under it? Also, are you forcing MTP at the trunk?

Yes the partition is selected.

And with or without MTP, it doesn't change anything. The call is still in one way.

Do you see SIP trunk configured with correct device pool having respective call manager on which you are receiving INVITE message....

I don't understand. In my device-pool, i have a group, and in this group i have my cucm.

But i don't have Asterisk in this group. Where can i do that ?

Actually i was wrong, when i go in Device > Trunk, the partition in the summary of the trunk doesn't appear.

In the partition i have my calling search space.

In the trunk, for inbound settings, i have the css.

So why does the partition not appear ?