<html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns:m="http://schemas.microsoft.com/office/2004/12/omml" xmlns="http://www.w3.org/TR/REC-html40"><head><META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=us-ascii"><meta name=Generator content="Microsoft Word 14 (filtered medium)"><style><!--
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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal>I know this is probably a very basic question for many on this list. But in troubleshooting an issue, I wanted to take a step back & ask the question. In Asterisk (or maybe all SIP), how do extensions stay registered with the SIP server?<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Do the extensions simply register repeatedly as a means of telling asterisk “I’m still here”, or are there actual keepalive packets that are transmitted to actually keep a TCP session alive? My guess is the former.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>But am I oversimplifying it? Is there more to the process?<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Thanks,<o:p></o:p></p><p class=MsoNormal>-<o:p></o:p></p><p class=MsoNormal><span style='font-size:14.0pt'>Doug Mortensen<o:p></o:p></span></p><p class=MsoNormal>Network Consultant<o:p></o:p></p><p class=MsoNormal><b>Impala Networks Inc<o:p></o:p></b></p><p class=MsoNormal><span style='font-size:10.0pt'>CCNA, MCSA, Security+, A+<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt'>Linux+, Network+, Server+<o:p></o:p></span></p><p class=MsoNormal>.<o:p></o:p></p><p class=MsoNormal><span style='font-size:10.0pt'><a href="http://www.impalanetworks.com"><span style='color:blue'>www.impalanetworks.com</span></a><o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt'>P: (505) 327-7300<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt'>F: (505) 327-7545<o:p></o:p></span></p><p class=MsoNormal>.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p></div></body></html>