Call files: dtmf detection error

outbound call answered is connected an extension but requires user to enter a few digits but none of them is recognised:

  1. call file
    Channel: SIP/4988880519@192.168.1.19
    Callerid: 71329908
    MaxRetries: 3
    RetryTime: 300
    WaitTime: 40
    Context: default
    Extension: 10076300
    Priority: 1

  2. sip.conf [ lan connection, no nat]
    [general]
    disallow=all
    allow=ulaw
    nat=yes
    externip=hidden
    localnet=hidden/hidden
    canreinvite=on
    qualify=yes
    dtmfmode=rfc2833 or auto ; neither works
    context=default
    allowoverlap=no
    bindport=5060
    bindaddr=0.0.0.0
    srvlookup=yes
    ;t38pt_udptl = yes

  3. extensions.conf

exten => 10076300,1,answer
; send dtmf could be heard
exten => 10076300,n,senddtmf(123)
; tried echo, entered dtmf could heard
;exten => 10076300,n,echo
exten => 10076300,n,Read(digito||3)
; no dtmf could be detected
exten => 10076300,n,SayDigits(${digito})
exten => 10076300,n,hangup

  1. logger.conf

console => dtmf (but no dtmf is detected)

  1. network

pri -> cisco as5350xm -> asterisk

  1. other

tried originate and manager api. both outbound call could detect dtmf. Only call files do not work!!!

pls advise.