asterisk users - Aug 2009 - Call no reject when receive 'PROGRESS with cause code 27 received' in zap channel

Hi, I have an asterisk connected with PRI (Zap channels).
If I try to call a number, and recieve cause code 27 because the line 553192
is out of service, but the call continue...is it ok?
Here the console messages


    -- Executing [98 at TRONCAL-PRI-76:5] Dial("Zap/1-1",
"Zap/g1/553192") in
new stack
    -- Requested transfer capability: 0x00 - SPEECH
    -- Called g1/553192
    -- PROGRESS with cause code 27 received
    -- Zap/2-1 is making progress passing it to Zap/1-1
    -- Zap/2-1 is proceeding passing it to Zap/1-1

Why asterisk don?t stop the call?
Thanks
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