I am running Asterisk for our phones all as been working fine until today with no changes  to the system I am getting the folowing error:

== Everyone is busy/congested at this time (1:0/1/0)
-- Auto fallthrough, channel 'SIP/601-00000020' status is 'CONGESTION'

And get this, its only for hard phones. I set up a soft phone on my computer, and outbound works fine, even using the same extensions as some of the hard phones. 

Incoming is fine. 

Full asterisk -rvvvvvv is:

== Using SIP RTP CoS mark 5
-- Executing [MY_MOBILE_NUMBER@phones:1] Dial("SIP/601-00000024", "SIP/OUTBOUND_NUMBER/MY_MOBILE_NUMBER") in new stack
== Using SIP RTP CoS mark 5
-- Called SIP/OUTBOUND_NUMBER/MY_MOBILE_NUMBER
== Extension Changed 601[phone-hints] new state InUse for Notify User 601
== Everyone is busy/congested at this time (1:0/1/0)
-- Auto fallthrough, channel 'SIP/601-00000024' status is 'CONGESTION'
== Extension Changed 601[phone-hints] new state Idle for Notify User 601
asterisk*CLI>


outgoing context in extensions.conf is:

exten => 111,1,Dial(${TAURANGA}/111)
exten => _5.,1,Dial(${TAURANGA}/${EXTEN}) ; Telecom numbers
exten => _92.,1,Dial(${TAURANGA}/${EXTEN}) ; TelstraClear numbers
exten => _21.,1,Dial(${TAURANGA}/${EXTEN}) ; vodafone numbers
exten => _28.,1,Dial(${TAURANGA}/${EXTEN}) ; 2talk numbers

exten => _1.,1,Dial(${TAURANGA}/${EXTEN}) ; telecom 1..
exten => _0800.,1,Dial(${TAURANGA}/${EXTEN}) ; telecom 0800...
exten => _0508.,1,Dial(${TAURANGA}/${EXTEN}) ; clear 0508...
exten => _00800.,1,Dial(${TAURANGA}/${EXTEN}) ; overseas 00800..

exten => _0900.,1,HangUp

exten => _03XXXXXXX,1,Dial(${CHRISTCHURCH}/${EXTEN})
exten => _04XXXXXXX,1,Dial(${TAURANGA}/${EXTEN})
exten => _06XXXXXXX,1,Dial(${TAURANGA}/${EXTEN})
exten => _07XXXXXXX,1,Dial(${TAURANGA}/${EXTEN})
exten => _09XXXXXXX,1,Dial(${AUCKLAND}/${EXTEN})
exten => _02.,1,Dial(${TAURANGA}/${EXTEN})
exten => _X.*,1,Dial(${TAURANGA}/${EXTEN})