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<p class="MsoNormal"><span style="font-family:"Georgia",serif;color:#00B050">I had a problem which I solved by turning on a FreeSWITCH option that logs a warning: “Enabling reg-deny-binding-fetch-and-no-lookup – this functionality is deprecated and will be
removed – let FS devs know if you think it should stay”. So here is me letting the FS devs know.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Georgia",serif;color:#00B050"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Georgia",serif;color:#00B050">The problem is to do with buggy user agents and their handling of multiple Contact headers in the 200 OK response to their REGISTER.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Georgia",serif;color:#00B050"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Georgia",serif;color:#00B050">My FreeSWITCH system uses mainly Snom phones and Zoiper soft phones. I allows multiple registrations and I have two sip profiles that the user agents connect to, one for Snoms and
one for Zoiper. They share a registration database with the dbname option.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Georgia",serif;color:#00B050"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Georgia",serif;color:#00B050">When multiple user agents register with the same credentials, the correct behaviour in the 200 OK to a REGISTER is to list all the user agents in multiple Contact headers with their
individual registration expiry times. This is exactly what FreeSWITCH does. However both clients (Snom and Zoiper) fail in a similar way:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Georgia",serif;color:#00B050"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Georgia",serif;color:#00B050">For their own reasons (<a href="https://www.zoiper.com/en/support/home/article/205/Zoiper%20Push%20Proxy">https://www.zoiper.com/en/support/home/article/205/Zoiper%20Push%20Proxy</a>)
Zoiper clients register with a 1 month expiry time. If in the 200 OK to a Snom the Zoiper contact header is first, then the Snom assumes that the header is meant for it, reads the large expiry time and uses it (and complains in its log if it’s over 14 days).
The FreeSWITCH registration for the Snom then expires after 1 hour, which what the Snom asked for in the first place. The Snom then doesn’t receive calls.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Georgia",serif;color:#00B050"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Georgia",serif;color:#00B050">Annoyingly a similar thing happens the other way round – if the Snom Contact header is first in the 200 OK sent to Zoiper, then the Zoiper client just looks at the first header, and
complains that the expiry time is too short with a message “You are connecting to a server with a low re-registration time. Battery life will not be optimal. Please contact your VoIP provider or PBX server administrator.”<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Georgia",serif;color:#00B050"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Georgia",serif;color:#00B050">(An aside: it would be interesting to know why returning multiple Contact headers is the defined behaviour, and what a user agent is supposed to do with the others headers, and therefore
what the consequences of not having them might be.)<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Georgia",serif;color:#00B050"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Georgia",serif;color:#00B050">We are contacting both Snom and Zoiper about this, but for the moment this is a useful FreeSWITCH option to cope with these user agents’ behaviours.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Georgia",serif;color:#00B050"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Georgia",serif;color:#00B050">Martin<o:p></o:p></span></p>
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