Dialplan:

[avxvp_lcr_test]
exten => _NXXNXXXXXX,1,NoOp(Least Cost Routing - Test)
exten => _NXXNXXXXXX,n,Macro(avxvp-getwtn)
exten => _NXXNXXXXXX,n,AGI(avxvp-lcr.agi|${WTN}|${EXTEN})
exten => _NXXNXXXXXX,n,NoOp(Number of Carriers Available: ${CARRIERS})
exten => _NXXNXXXXXX,n,Set(i=1)
exten => _NXXNXXXXXX,n,While($[${i} <= ${CARRIERS}])
exten => _NXXNXXXXXX,n,SayNumber(${i})
exten => _NXXNXXXXXX,n,Set(CARRIER=${LCR_CARR}${i})
exten => _NXXNXXXXXX,n,SayAlpha(${CARRIER})
exten => _NXXNXXXXXX,n,Set(i=$[${i} + 1])
exten => _NXXNXXXXXX,n,EndWhile
exten => _NXXNXXXXXX,n,Playtones(info)
exten => _NXXNXXXXXX,n,Wait(1)
exten => _NXXNXXXXXX,n,Playback(cannot-complete-as-dialed)
exten => _NXXNXXXXXX,n,Hangup


Console Output:

    -- Executing [6785551111@avxvp_lcr_test:3] AGI("SIP/mysipdomain.net-b6b13888", "avxvp-lcr.agi|8435551111|6785551111") in new stack
    -- Launched AGI Script /var/lib/asterisk/agi-bin/avxvp-lcr.agi
    -- AGI Script Executing Application: (NoOp) Options: (Starting LCR AGI)
    -- AGI Script Executing Application: (Set) Options: (CARRIERS=2)
    -- AGI Script Executing Application: (Set) Options: (LCR_CARR0=GF0)
    -- AGI Script Executing Application: (Set) Options: (LCR_RATE0=0.00410)
    -- AGI Script Executing Application: (Set) Options: (LCR_TYPE0=INTERSTATE)
    -- AGI Script Executing Application: (Set) Options: (LCR_CARR1=SS0)
    -- AGI Script Executing Application: (Set) Options: (LCR_RATE1=0.01200)
    -- AGI Script Executing Application: (Set) Options: (LCR_TYPE1=INTERSTATE)
    -- AGI Script avxvp-lcr.agi completed, returning 0
    -- Executing [6785551111@avxvp_lcr_test:4] NoOp("SIP/mysipdomain.net-b6b13888", "Number of Carriers Available: 2") in new stack
    -- Executing [6785551111@avxvp_lcr_test:5] Set("SIP/mysipdomain.net-b6b13888", "i=1") in new stack
    -- Executing [6785551111@avxvp_lcr_test:6] While("SIP/mysipdomain.net-b6b13888", "1") in new stack
    -- Executing [6785551111@avxvp_lcr_test:7] SayNumber("SIP/mysipdomain.net-b6b13888", "1") in new stack
    -- <SIP/mysipdomain.net-b6b13888> Playing 'digits/1' (language 'en')
    -- Executing [6785551111@avxvp_lcr_test:8] Set("SIP/mysipdomain.net-b6b13888", "CARRIER=1") in new stack
    -- Executing [6785551111@avxvp_lcr_test:9] SayAlpha("SIP/mysipdomain.net-b6b13888", "1") in new stack
    -- <SIP/mysipdomain.net-b6b13888> Playing 'digits/1' (language 'en')
  == Spawn extension (avxvp_lcr, 8438334147, 9) exited non-zero on 'SIP/mysipdomain.net-b772dd00'
    -- Executing [6785551111@avxvp_lcr_test:10] Set("SIP/mysipdomain.net-b6b13888", "i=2") in new stack
    -- Executing [6785551111@avxvp_lcr_test:11] EndWhile("SIP/mysipdomain.net-b6b13888", "") in new stack
    -- Executing [6785551111@avxvp_lcr_test:6] While("SIP/mysipdomain.net-b6b13888", "1") in new stack
    -- Executing [6785551111@avxvp_lcr_test:7] SayNumber("SIP/mysipdomain.net-b6b13888", "2") in new stack