[local]
exten => 5678,1,Dial(SIP/5678,10)
exten => 5678,n,Playback(vm-nobodyavail)
exten => 5678,n,Hangup()

exten => 5679,1,Dial(SIP/5679,10)
exten => 5679,n,Playback(vm-nobodyavail)
exten => 5679,n,Hangup()