Taking a quick look this is the first thing that I saw.
Line 154
full:[2020-03-30 11:04:40] VERBOSE[13043][C-00000022] pbx.c: Executing [s@macro-dialout-trunk:34] NoOp(“PJSIP/204-0000003e”, “Dial failed for some reason with DIALSTATUS = CHANUNAVAIL and HANGUPCAUSE = 21”) in new stack
Someone else may be able to see more in there.