[asterisk-users] prompt playing problem

[unplug]

Anyone can help me to solve the problem about playing the prompt?  Is
it related to the package problem?  Anyone can give me a clue to find
out the solution?  Thx.

I have a simple dial plan to play a voice prompt as follow.
exten => 33334444,1,Answer()
exten => 33334444,2,Playback(you-have-reached-a-test-number)
exten => 33334444,3,Hangup()
where number is a valid phone number.

When I use a IP phone which connected to asterisk directly and dial
the number, the voice prompt plays without problem.
When I use a mobile phone and dial the number, the voice prompt also
plays without problem.
   -- Executing Answer("SIP/203.191.26.242-087345a0", "")
    -- Executing Playback("SIP/203.191.26.242-087345a0",
"you-have-reached-a-test-number")
    -- Playing 'you-have-reached-a-test-number' (language 'en')
    -- Executing Hangup("SIP/203.191.26.242-087345a0", "")
  == Spawn extension (prompttest, 33334444, 3) exited non-zero on
'SIP/203.191.26.242-087345a0'

However, when I use a normal phone (PSTN) and dial the number, there
is a looping in CLI and the prompt failed to play.  Finally the call
terminated after timeout.
    -- Executing Answer("SIP/203.191.26.242-0872f170", "")
    -- Executing Playback("SIP/203.191.26.242-0872f170",
"you-have-reached-a-test-number")
    -- Playing 'you-have-reached-a-test-number' (language 'en')
  == Spawn extension (prompttest, 33334444, 2) exited non-zero on
'SIP/203.191.26.242-0872f170'
    -- Executing Answer("SIP/203.191.26.242-08737358", "")
    -- Executing Playback("SIP/203.191.26.242-08737358",
"you-have-reached-a-test-number")
    -- Playing 'you-have-reached-a-test-number' (language 'en')
  == Spawn extension (prompttest, 33334444, 2) exited non-zero on
'SIP/203.191.26.242-08737358'
    -- Executing Answer("SIP/203.191.26.242-087345a0", "")
    -- Executing Playback("SIP/203.191.26.242-087345a0",
"you-have-reached-a-test-number")
    -- Playing 'you-have-reached-a-test-number' (language 'en')
    -- Executing Answer("SIP/203.191.26.242-0874a600", "")
    -- Executing Playback("SIP/203.191.26.242-0874a600",
"you-have-reached-a-test-number")
    -- Playing 'you-have-reached-a-test-number' (language 'en')
  == Spawn extension (prompttest, 33334444, 2) exited non-zero on
'SIP/203.191.26.242-087345a0'
  == Spawn extension (prompttest, 33334444, 2) exited non-zero on
'SIP/203.191.26.242-0874a600'
    -- Executing Answer("SIP/203.191.26.242-087345a0", "")
    -- Executing Playback("SIP/203.191.26.242-087345a0",
"you-have-reached-a-test-number")
    -- Playing 'you-have-reached-a-test-number' (language 'en')
  == Spawn extension (prompttest, 33334444, 2) exited non-zero on
'SIP/203.191.26.242-087345a0'
    -- Executing Answer("SIP/203.191.26.242-08737400", "")
    -- Executing Playback("SIP/203.191.26.242-08737400",
"you-have-reached-a-test-number")
    -- Playing 'you-have-reached-a-test-number' (language 'en')
  == Spawn extension (prompttest, 33334444, 2) exited non-zero on
'SIP/203.191.26.242-08737400'
    -- Executing Answer("SIP/203.191.26.242-087345a0", "")
    -- Executing Playback("SIP/203.191.26.242-087345a0",
"you-have-reached-a-test-number")
    -- Playing 'you-have-reached-a-test-number' (language 'en')