[asterisk-users] Failover SIP logic

[Jeremy Mann]

I need some extensions logic assistance, I'm trying to dial out one of multiple SIP trunks, in sequence.  I need to detect a busy SIP trunk(I only allow 1 call per trunk) and roll over to a second or third depending on that busy status

Here's what I've got for a macro thusfar, but it's not working(fails if the 1st trunk is busy)
extensions.conf:

[globals]
trunk_1 => SIP/trunk1
trunk_2 => SIP/trunk2
trunk_3 => SIP/trunk3

[macro-trunkdial]
exten => s,1,Dial(${trunk_1}/${ARG1})
exten => s,2,Hangup()
exten => s,102,Dial(${trunk_2}/${ARG1})
exten => s,103,Hangup()
exten => s,203,Dial(${trunk_3}/${ARG1})
exten => s,204,Hangup()

[from-internal]
exten => _NXXNXXXXXX,1,Macro(trunkdial,+1${EXTEN})
exten => _1NXXNXXXXXX,1,Macro(trunkdial,+${EXTEN})

sip.conf:

[trunk1]
host=xxx.xxx.xxx.xxx
port=5060
type=peer
allow=ulaw
dtmfmode=rfc2833
canreinvite=no
reinvite=no
nat=no
fromuser=+xxxxxxxxxxx
call-limit=1

[trunk2]
host=xxx.xxx.xxx.xxx
port=5060
type=peer
allow=ulaw
dtmfmode=rfc2833
canreinvite=no
reinvite=no
nat=no
fromuser=+xxxxxxxxxxx
call-limit=1

[trunk3]
host=xxx.xxx.xxx.xxx
port=5060
type=peer
allow=ulaw
dtmfmode=rfc2833
canreinvite=no
reinvite=no
nat=no
fromuser=+xxxxxxxxxxx
call-limit=1

Here's asterisk output when someone dials out:
Executing [xxxxxxxxxx at from-internal:1] Macro("SIP/6001-007e2840", "trunkdial|+1xxxxxxxxxx") in new stack
    -- Executing [s at macro-trunkdial:1] Dial("SIP/6001-007e2840", "SIP/trunk1/+1xxxxxxxxxx") in new stack
[Sep 10 09:06:52] ERROR[16253]: chan_sip.c:3192 update_call_counter: Call to peer 'trunk1' rejected due to usage limit of 1
    -- Couldn't call trunk1/+1xxxxxxxxxx
  == Everyone is busy/congested at this time (0:0/0/0)
    -- Executing [s at macro-trunkdial:2] Hangup("SIP/6001-007e2840", "") in new stack

I don't want the dialplan to cascade like:

exten => 1,dial...
exten => 2,dial...

Because if the remote end hangs up I don't want it going to priority 2 to dial out again(in case my user doesn't hit hang-up on their end) so I need logic to detect a busy channel and jump to the next section..


Thanks for any help.

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