TRUNK Dial failed due to CHANUNAVAIL HANGUPCAUSE: 21 - failing through to other trunks

[Stewart1 (Stewart)]

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Solved: Outbound calls failing on trunk

Hello all. I have an issue where outbound calls fail instantly with a ‘busy line’ message on a trunk over which inbound calls work fine. The PBX has another trunk to an SBC and inbound/outbound calls work. I’ve used the same configuration for both, inbound and outbound rules also. Both trunks go over dedicated L2 circuits - no registration involved. The 20959901 extension belongs to a range allocated to us by the remote party. The 20930315 extension is a valid extension on the remote PBX. Calls…

If you have an Outbound Proxy set up, that could be your issue (and solution).
However, sip.kabelfon.vodafone.de has an A record that resolves to 88.134.209.241, so it seems that Outbound Proxy should not be required.

If you still have trouble, please post screenshots of the pjsip settings for your trunk, both General and Advanced tabs.