Merged revisions 274157 via svnmerge from

https://origsvn.digium.com/svn/asterisk/branches/1.4

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  r274157 | mmichelson | 2010-07-06 09:29:23 -0500 (Tue, 06 Jul 2010) | 16 lines
  
  Fix problem with RFC 2833 DTMF not being accepted.
  
  A recent check was added to ensure that we did not erroneously
  detect duplicate DTMF when we received packets out of order.
  The problem was that the check did not account for the fact that
  the seqno of an RTP stream will roll over back to 0 after hitting
  65535. Now, we have a secondary check that will ensure that the
  seqno rolling over will not cause us to stop accepting DTMF.
  
  (closes issue #17571)
  Reported by: mdeneen
  Patches: 
        rtp_seqno_rollover.patch uploaded by mmichelson (license 60)
  Tested by: richardf, maxochoa, JJCinAZ
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git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@274164 65c4cc65-6c06-0410-ace0-fbb531ad65f3