asterisk users - Jan 2010 - Will SIP connection stop automaticlly when detect no voice between the channel after a period of time?

hi,

in my test, i noticed that sip connection will hangup automaticlly
when no speaks between the channel. about half a minute.

is this the asterisk inner mechanism or is my configuration error?

Thanks!

messages on the cli as follow:

    -- SIP/1003-0000001d is ringing
    -- SIP/1003-0000001d answered SIP/1004-0000001c
    -- Stopped music on hold on SIP/1004-0000001c
[Jan 18 10:08:42] WARNING[17022]: app_queue.c:3268 try_calling: The
device state of this queue member, Zhang Jianming, is still 'Not in
Use' when it probably should not be! Please check UPGRADE.txt for
correct configuration settings.
    -- Packet2Packet bridging SIP/1004-0000001c and SIP/1003-0000001d
    -- Executing Playback("SIP/1004-0000001c", "vm-goodbye")
[Jan 18 10:09:13] WARNING[17022]: file.c:764 ast_readaudio_callback:
Failed to write frame
    -- <SIP/1004-0000001c> Playing 'vm-goodbye' (language
'en')
[Jan 18 10:09:13] WARNING[17022]: app_playback.c:440 playback_exec:
ast_streamfile failed on SIP/1004-0000001c for vm-goodbye
  == Spawn extension (95040654321, 1, 2) exited non-zero on
'SIP/1004-0000001c'
[Jan 18 10:09:18] NOTICE[16700]: chan_sip.c:16209
handle_request_subscribe: Received SIP subscribe for peer without
mailbox: 1003

-- 
Best regards,
Sucan