-- Executing Set("SIP/311-2bb1", "CALLERID(number)=860XXXXXXX") in new stack
    -- Executing SetCallerID("SIP/311-2bb1", ""L"") in new stack
    -- Executing Dial("SIP/311-2bb1", "Zap/1/18X0X245X00") in new stack
    -- Requested transfer capability: 0x00 - SPEECH
    -- Called 1/18XXXXXX00
    -- Channel 0/1, span 1 got hangup
    -- Channel 0/1, span 1 received AOC-E charging 0 units
    -- Hungup 'Zap/1-1'
  == Everyone is busy/congested at this time (1:0/0/1)
  == Auto fallthrough, channel 'SIP/311-2bb1' status is 'CHANUNAVAIL'

extensions.conf:

[trunklocal]
;
; Local seven-digit dialing accessed through trunk interface
;
;exten => _9NXXXXXX,1,Dial(${TRUNKVOIP}/${EXTEN:${TRUNKMSD}})
exten => _NXXXXXX,1,Set(CALLERID(number)=860XXXXXXX)
exten => _NXXXXXX,2,SetCallerId,"L"
exten => _NXXXXXX,n,Dial(${TRUNKPSTN}/1860${EXTEN:${TRUNKMSD}})