As of October 2008, the default Polycom provisioning file provided by trixbox's Endpoint Manager is missing a small portion to get intercom working. After you ran setup-polycom in SSH to set up the Polycom provisioning files, edit /tftpboot/sip.cfg
There is a line containing the following:
<alertInfo voIpProt.SIP.alertInfo.1.value="" voIpProt.SIP.alertInfo.1.class=""/>
This line must be replaced with:
<alertInfo voIpProt.SIP.alertInfo.1.value="Ring Answer" voIpProt.SIP.alertInfo.1.class="4"/>
Additionally, by default, when paging another Polycom phone, the phone will ring twice before the page is initiated. To eliminate the two rings, look at the line containing the following:
<RING_ANSWER se.rt.4.name="Ring Answer" se.rt.4.type="ring-answer" se.rt.4.timeout="2000" se.rt.4.ringer="2" se.rt.4.callWait="6" se.rt.4.mod="1"/>
Replace it with this line:
<RING_ANSWER se.rt.4.name="Ring Answer" se.rt.4.type="ring-answer" se.rt.4.timeout="2" se.rt.4.ringer="2" se.rt.4.callWait="6" se.rt.4.mod="1"/>
Make sure your phones are getting provisioned properly so that it can read the changes and update the new settings. To update the settings, simply reboot your telephone.