Asterisk Script Help

Can someone tell me what this script does? I inherited this script from someone who worked on our old Trixbox Voicemail Server. I’m trying to figure out how to read it.

[metaswitch]
exten => _.,1,Noop(Replacing DID with RDNIS)
; Set Caller ID to callers number
exten => _.,2,NoOp({CALLERID(num)},{CALLERID(rdnis)},{CALLERID(dnid)}) exten => _.,3,Noop(Replacing DID with RDNIS) exten => _.,4,Set(pseudodid={CALLERID(rdnis)})
exten => _.,5,GotoIf(["{CALLERID(rdnis)}" = “”]?6:8)
exten => _.,6,VoiceMailMain({CALLERID(num)}) exten => _.,7,Hangup() ; dump if pseudodid doesn't exist exten => _.,8,Set(MYMAILBOX={CALLERID(rdnis)}@default)
exten => _.,9,MailboxExists({MYMAILBOX}) exten => _.,10,NoOp({VMBOXEXISTSSTATUS})
exten => _.,11,GotoIf(["{VMBOXEXISTSSTATUS}" = “SUCCESS”]?27:21)
exten => _.,21,Playback(error-number)
exten => _.,22,Playback(digits/4)
exten => _.,23,Playback(digits/0)
exten => _.,24,Playback(digits/3)
exten => _.,25,Playback(goodbye)
exten => _.,26,Hangup()
exten => _.,27,Goto(from-trunk,${pseudodid},1)
exten => _.,28,Hangup()

If you cant understand that code it is worthless at least for me , go more in deep because they will arrive a ton of questions due to the lack of the basic dial plan knowledge.

Also you re missing $

You need to use </>, on the forum edit bar, to mark dialplan as preformatted text. One of the effects of not doing this seems to be lost $s.

We seem to have had an increase in this particular problem within the last month. I’m not sure why.