FreePBX 15, two trunks configured identically, outbound routes configured identically, both registered with same VOIP provider and working. One extension can call out on trunk 1, but not trunk 2. All I’m doing is switching between “Allowed Routes” in extension configuration. Checking trunk 1 works, trunk 2, I get “all circuits busy.”
The log reads: “TRUNK Dial failed due to CHANUNAVAIL HANGUPCAUSE: 21”
True, but my goal was solely to get the two trunks working, not to debug either my VOIP provider or FreePBX. I have neither the technical expertise nor the time to find out the reasons.
Accordingly, if anyone else is experiencing this with voip.ms, an interim solution is to use chan_sip and pjsip.