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<div class=Section1 style='layout-grid:18.0pt'>
<p class=MsoNormal><font size=3 face="Book Antiqua"><span lang=EN-US
style='font-size:12.0pt'>Hi,<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=3 face="Book Antiqua"><span lang=EN-US
style='font-size:12.0pt'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=3 face="Book Antiqua"><span lang=EN-US
style='font-size:12.0pt'>I am writing the channel driver of the FXS/FXO ports of
our VoIP gateway board.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=3 face="Book Antiqua"><span lang=EN-US
style='font-size:12.0pt'>When talking with a SIP softphone (SJPhone), I found
that my write() function will be continuously called five times about every 100
ms.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=3 face="Book Antiqua"><span lang=EN-US
style='font-size:12.0pt'>That is, the interval between these five calls is
almost zero. After the five calls, it must wait about 100 ms for next 5 calls. <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=3 face="Book Antiqua"><span lang=EN-US
style='font-size:12.0pt'>However, the sample number of each RTP packet is set as
160, i.e. 20 ms per packet. <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=3 face="Book Antiqua"><span lang=EN-US
style='font-size:12.0pt'>By capturing the packets sent by SJPhone, we found
that it really sends one voice RTP packet every 20 ms.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=3 face="Book Antiqua"><span lang=EN-US
style='font-size:12.0pt'>It seems that Asterisk buffers the incoming voice
packets from network and then sends a number of them to the other call leg.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=3 face="Book Antiqua"><span lang=EN-US
style='font-size:12.0pt'>Could you tell me how does Asterisk deal with the incoming
packets? And, may we adjust the buffering delay?<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=3 face="Book Antiqua"><span lang=EN-US
style='font-size:12.0pt'>Thanks a lot.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=3 face="Book Antiqua"><span lang=EN-US
style='font-size:12.0pt'><o:p> </o:p></span></font></p>
<p class=MsoNormal style='layout-grid-mode:char'><font size=2
face="Book Antiqua"><span lang=EN-US style='font-size:10.0pt'>Sincerely Yours,</span></font><span
lang=EN-US><o:p></o:p></span></p>
<p class=MsoNormal style='layout-grid-mode:char'><font size=2
face="Book Antiqua"><span lang=EN-US style='font-size:10.0pt'>--</span></font><span
lang=EN-US><o:p></o:p></span></p>
<p class=MsoNormal style='layout-grid-mode:char'><font size=2
face="Book Antiqua"><span lang=EN-US style='font-size:10.0pt'>Guan-Hsiung Liaw
(</span></font><font size=2 face=標楷體><span style='font-size:10.0pt;font-family:
標楷體'>廖冠雄</span></font><font size=2><span lang=EN-US style='font-size:10.0pt'>)</span></font><span
lang=EN-US><o:p></o:p></span></p>
<p class=MsoNormal style='layout-grid-mode:char'><font size=2
face="Book Antiqua"><span lang=EN-US style='font-size:10.0pt'>Assistant
Professor</span></font><span lang=EN-US><o:p></o:p></span></p>
<p class=MsoNormal style='layout-grid-mode:char'><font size=2
face="Book Antiqua"><span lang=EN-US style='font-size:10.0pt'>Department of
Information Engineering</span></font><span lang=EN-US><o:p></o:p></span></p>
<p class=MsoNormal style='layout-grid-mode:char'><u1:place u2:st="on"><u1:PlaceName u2:st="on"><st1:place
w:st="on"><st1:PlaceName w:st="on"><font size=2 face="Book Antiqua"><span
lang=EN-US style='font-size:10.0pt'>I-<span class=spelle>Shou</span></span></font></st1:PlaceName></st1:place><font
size=2><span lang=EN-US style='font-size:10.0pt'></u1:PlaceName> <u1:PlaceType u2:st="on"><st1:PlaceType
w:st="on">University</u1:PlaceType></st1:PlaceType></span></font></st1:place><span
lang=EN-US><o:p></o:p></span></p>
<p class=MsoNormal style='layout-grid-mode:char'><font size=2
face="Book Antiqua"><span lang=EN-US style='font-size:10.0pt'>1, Section 1, <u1:Street u2:st="on"><u1:address u2:st="on"><st1:Street
w:st="on"><st1:address w:st="on"><span class=spelle>Hsueh</span>-Cheng Rd.</u1:address></u1:Street></st1:address></st1:Street>,
</span></font><span lang=EN-US><o:p></o:p></span></p>
<p class=MsoNormal style='layout-grid-mode:char'><font size=2
face="Book Antiqua"><span lang=EN-US style='font-size:10.0pt'>Ta-Hsu <span
class=spelle>Hsiang</span>, <u1:place u2:st="on"><u1:PlaceName u2:st="on"><st1:place
w:st="on"><st1:PlaceName w:st="on"><span class=spelle>Kaohsiung</u1:PlaceName></span></st1:PlaceName></st1:place>
<u1:PlaceType u2:st="on">County</u1:PlaceType></u1:PlaceType></u1:place>, </span></font><span
lang=EN-US><o:p></o:p></span></p>
<p class=MsoNormal style='layout-grid-mode:char'><u1:country-region u2:st="on"><u1:place u2:st="on"><st1:country-region
w:st="on"><st1:place w:st="on"><font size=2 face="Book Antiqua"><span
lang=EN-US style='font-size:10.0pt'>Taiwan</span></font></st1:place></st1:country-region></u1:place></u1:country-region><font
size=2><span lang=EN-US style='font-size:10.0pt'> 840, R.O.C.</span></font><span
lang=EN-US><o:p></o:p></span></p>
<p class=MsoNormal style='layout-grid-mode:char'><font size=3
face="Book Antiqua"><span lang=EN-US style='font-size:12.0pt'> <o:p></o:p></span></font></p>
<p class=MsoNormal style='layout-grid-mode:char'><font size=2
face="Book Antiqua"><span lang=EN-US style='font-size:10.0pt'>Tel:
886-7-6577711 ext. 6529</span></font><span lang=EN-US><o:p></o:p></span></p>
<p class=MsoNormal style='layout-grid-mode:char'><font size=2
face="Book Antiqua"><span lang=EN-US style='font-size:10.0pt'>e-mail:
ghliaw@isu.edu.tw</span></font><span lang=EN-US><o:p></o:p></span></p>
<p class=MsoNormal><font size=3 face="Book Antiqua"><span lang=EN-US
style='font-size:12.0pt'><o:p> </o:p></span></font></p>
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